Homologous 28-kilodalton immunodominant protein genes of Ehrlichia canis and uses thereof

ABSTRACT

The present invention is directed to the cloning, sequencing and expression of homologous immunoreactive 28-kDa protein genes, p28-1, -2, -3, -5; -6, -7, -9, from a polymorphic multiple gene family of  Ehrlichia canis . Further disclosed is a multigene locus encoding all nine homologous 28-kDa protein genes of  Ehrlichia canis . Recombinant  Ehrlichia canis  28-kDa proteins react with convalescent phase antiserum from an  E. canis -infected dog, and may be useful in the development of vaccines and serodiagnostics that are particularly effective for disease prevention and serodiagnosis.

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This patent application is a continuation-in-part of U.S. application Ser. No. 09/261,358, filed Mar. 3, 1999, which is a continuation-in-part of U.S. application Ser. No. 09/201,458, filed Nov. 30, 1998.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates generally to the field of molecular biology. More specifically, the present invention relates to molecular cloning and characterization of homologous 28-kDa protein genes in Ehrlichia canis, a multigene locus encoding the 28-kDa homologous proteins of Ehrlichia canis and uses thereof.

[0004] 2. Description of the Related Art

[0005] Canine ehrlichiosis, also known as canine tropical pancytopenia, is a tick-borne rickettsial disease of dogs first described in Africa in 1935 and the United States in 1963 (Donatien and Lestoquard, 1935; Ewing, 1963). The disease became better recognized after an epizootic outbreak occurred in United States military dogs during the Vietnam War (Walker et al., 1970)

[0006] The etiologic agent of canine ehrlichiosis is Ehrlichia canis, a small, gram-negative, obligate intracellular bacterium which exhibits tropism for mononuclear phagocytes (Nyindo et al., 1971) and is transmitted by the brown dog tick, Rhipicephalus sanguineus (Groves et al., 1975). The progression of canine ehrlichiosis occurs in three phases, acute, subclinical and chronic. The acute phase is characterized by fever, anorexia, depression, lymphadenopathy and mild thrombocytopenia (Troy and Forrester, 1990). Dogs typically recover from the acute phase, but become persistently infected carriers of the organism without clinical signs of disease for months or even years (Harrus et al., 1998). A chronic phase develops in some cases that is characterized by thrombocytopenia, hyperglobulinemia, anorexia, emaciation, and hemorrhage, particularly epistaxis, followed by death (Troy and Forrester, 1990).

[0007] Regulation of surface antigenicity may be an important mechanism for the establishment of such persistent infections in the host. Although disease pathogenesis is poorly understood, multigene families described in members of the related genera Ehrlichia, Anaplasma, and Cowdria may be involved in variation of major surface antigen expression thereby evading immune surveillance. Anaplasma marginale, an organism closely related to E. canis, exhibits variation of major surface protein 3 (msp-3) genes resulting in antigenic polymorphism among strains (Alleman et al., 1997).

[0008] Molecular taxonomic analysis based on the 16S rRNA gene has determined that E. canis and E. chaffeensis, the etiologic agent of human monocytic ehrlichiosis (HME), are closely related (Anderson et al., 1991; Anderson et al., 1992; Dawson et al., 1991; Chen et al., 1994). Considerable cross reactivity of the 64, 47, 40, 30, 29 and 23-kDa antigens between E. canis and E. chaffeensis has been reported (Chen et al., 1994; Chen et al., 1997; Rikihisa et al., 1994; Rikihisa et al., 1992). Analysis of immunoreactive antigens with human and canine convalescent phase sera by immunoblot has resulted in the identification of numerous immunodominant proteins of E. canis, including a 30-kDa protein (Chen et al., 1997). In addition, a 30-kDa protein of E. canis has been described as a major immunodominant antigen recognized early in the immune response that is antigenically distinct from the 30-kDa protein of E. chaffeensis (Rikihisa et al., 1992; Rikihisa et al., 1994). Other immunodominant proteins of E. canis with molecular masses ranging from 20 to 30-kDa have also been identified (Brouqui et al., 1992; Nyindo et al., 1991; Chen et al., 1994; Chen et al., 1997).

[0009] Homologous 28-32 kDa immunodominant proteins encoded by multigene families have been reported in related organisms including, E. chaffeensis and Cowdria ruminantium (Sulsona et al., 1999; Ohashi et al., 1998a; Reddy et al., 1998). Recently, characterization of a 21 member multigene family encoding proteins of 23 to 28-kDa has been described in E. chaffeensis (Yu et al., 2000). The E. chaffeensis 28-kDa outer membrane proteins are surface exposed, and contain three major hypervariable regions (Ohashi et al., 1998a). The recombinant E. chaffeensis P28 appeared to provide protection against homologous challenge infection in mice, and antisera produced against the recombinant protein cross reacted with a 30-kDa protein of E. canis (Ohashi et al., 1998a). Diversity in the p28 gene among E. chaffeensis isolates has been reported (Yu et al., 1999a), and studies using monoclonal antibodies have further demonstrated diversity in the expressed P28 proteins (Yu et al., 1993). Conversely, complete conservation of a p28 genes in geographically different isolates of E. canis has been reported and suggests that E. canis may be conserved in North America (McBride et al., 1999, 2000).

[0010] The prior art is deficient in the lack of cloning and characterization of new homologous 28-kDa immunoreactive protein genes of Ehrlichia canis and a single multigene locus containing the homologous 28-kDa protein genes. Further, The prior art is deficient in the lack of recombinant proteins of such immunoreactive genes of Ehrlichia canis. The present invention fulfills this long-standing need and desire in the art.

SUMMARY OF THE INVENTION

[0011] Certain embodiments of the present invention describe the molecular cloning, sequencing, characterization, and expression of homologous mature 28-kDa immunoreactive protein genes of Ehrlichia canis (designated p28-1, -2, -3, -5, -6, -7, -9), and the identification of a single locus (10,677-bp) containing nine 28-kDa protein genes of Ehrlichia canis (p28-1 to p28-9). Eight of the p28 genes were located on one DNA strand, and one p28 gene was found on the complementary strand. The nucleic acid homology among the nine p28 gene members was 37 to 75%, and the amino acid homology ranged from 28 to 72%.

[0012] In one embodiment of the present invention, there are provided DNA sequences encoding a 30-kDa immunoreactive protein of Ehrlichia canis. Preferably, the protein has an amino acid sequence selected from the group consisting of SEQ ID No. 2, 4, 6, 40, 42, 44, 46 and the gene has a nucleic acid sequence selected from the group consisting of SEQ ID No. 1, 3, 5, 39, 41, 43, 45 and is a member of a polymorphic multiple gene family. Generally, the protein has an N-terminal signal sequence which may be cleaved after post-translational process resulting in the production of a mature 28-kDa protein. Furthermore, the genes encoding 28-kDa proteins are preferably contained in a single multigene locus, which has the size of 10,677 bp and encodes nine homologous 28-kDa proteins of Ehrlichia canis.

[0013] In another embodiment of the present invention, there is provided an expression vector comprising a gene encoding a 28-kDa immunoreactive protein of Ehrlichia canis and capable of expressing the gene when the vector is introduced into a cell.

[0014] In still another embodiment of the present invention, there is provided a recombinant protein comprising an amino acid sequence selected from the group consisting of SEQ ID No. 2, 4, 6, 40, 42, 44, and 46. Preferably, the amino acid sequence is encoded by a nucleic acid sequence selected from the group consisting of SEQ ID No. 1, 3, 5, 39, 41, 43, and 45. Preferably, the recombinant protein comprises four variable regions which may be surface exposed, hydrophilic and antigenic. The recombinant protein may be useful as an antigen.

[0015] In yet another embodiment of the present invention, there is provided a method of producing the recombinant protein, comprising the steps of obtaining a vector that comprises an expression region comprising a sequence encoding the amino acid sequence selected from the group consisting of SEQ ID No. 2, 4, 6, 40, 42, 44, and 46 operatively linked to a promoter; transfecting the vector into a cell; and culturing the cell under conditions effective for expression of the expression region.

[0016] The invention may also be described in certain embodiments as a method of inhibiting Ehrlichia canis infection in a subject comprising the steps of: identifying a subject prior to exposure or suspected of being exposed to or infected with Ehrlichia canis; and administering a composition comprising a 28-kDa antigen of Ehrlichia canis in an amount effective to inhibit an Ehrlichia canis infection. The inhibition may occur through any means such as, e.g., the stimulation of the subject's humoral or cellular immune responses, or by other means such as inhibiting the normal function of the 28-kDa antigen, or even competing with the antigen for interaction with some agent in the subject's body.

[0017] Other and further aspects, features, and advantages of the present invention will be apparent from the following description of the presently preferred embodiments of the invention given for the purpose of disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] So that the matter in which the above-recited features, advantages and objects of the invention, as well as others which will become clear, are attained and can be understood in detail, more particular descriptions of the invention briefly summarized above may be had by reference to certain embodiments thereof which are illustrated in the appended drawings. These drawings form a part of the specification. It is to be noted, however, that the appended drawings illustrate preferred embodiments of the invention and therefore are not to be considered limiting in their scope.

[0019]FIG. 1 shows nucleic acid sequence (SEQ ID No. 1 and deduced amino acid sequence (SEQ ID No. 2) of p28-7 gene including adjacent 5′ and 3′ non-coding sequences. The ATG start codon and TAA termination are shown in bold, and the 23 amino acid leader signal sequence is underlined.

[0020]FIG. 2 shows SDS-PAGE of expressed 50-kDa recombinant p28-7-thioredoxin fusion protein (Lane 1, arrow) and 16-kDa thioredoxin control (Lane 2, arrow), and corresponding immunoblot of recombinant p28-7-thioredoxin fusion protein recognized by covalescent-phase E. canis canine antiserum (Lane 3). Thiroredoxin control was not detected by E. canis antiserum (not shown).

[0021]FIG. 3 shows amino acid sequences alignment of p28-7 protein (ECa28-1, SEQ ID NO. 2), p28-5 protein (ECa28SA2, partial sequence, SEQ ID NO. 7), p28-4 protein (ECa28SA1, SEQ ID NO. 8), E. chaffeensis P28 (SEQ ID NO. 9), E. chaffeensis OMP-1 family (SEQ ID NOs: 10-14) and C. ruminantium MAP-1 protein (SEQ ID NO. 15). The p28-7 amino acid sequence is presented as the consensus sequence. Amino acids not shown are identical to p28-7 and are represented by a dot. Divergent amino acids are shown with the corresponding one letter abbreviation. Gaps introduced for maximal alignment of the amino acid sequences are denoted with a dash. Variable regions are underlined and denoted (VR1, VR2, VR3, and VR4). The arrows indicate the predicted signal peptidase cleavage site for the signal peptide.

[0022]FIG. 4 shows phylogenetic relatedness of E. canis p28-7 (ECa28-1), p28-5 (ECa28SA2, partial sequence), p28-4 (ECa28SA1), members of the E.chaffeensis omp-1 multiple gene family, and C. rumanintium map-1 protein from deduced amino acid sequences utilizing unbalanced tree construction. The length of each pair of branches represents the distance between the amino acid sequence of the pairs. The scale measures the distance between sequences.

[0023]FIG. 5 shows Southern blot analysis of E. canis genomic DNA completely digested with six individual restriction enzymes and hybridized with a p28-7 DIG-labeled probe (Lanes 2-7); DIG-labeled molecular weight markers (Lanes 1 and 8).

[0024]FIG. 6 shows comparison of predicted protein characteristics of E. canis p28-7 (ECa28-1, Jake strain) and E. chaffeensis P28 (Arkansas strain). Surface probability predicts the surface residues by using a window of hexapeptide. A surface residue is any residue with a >2.0 nm² of water accessible surface area. A hexapeptide with a value higher than 1 was considered as surface region. The antigenic index predicts potential antigenic determinants. The regions with a value above zero are potential antigenic determinants. T-cell motif locates the potential T-cell antigenic determinants by using a motif of 5 amino acids with residue 1-glycine or polar, residue 2-hydrophobic, residue 3-hydrophobic, residue 4-hydrophobic or proline, and residue 5-polar or glycine. The scale indicates amino acid positions.

[0025]FIG. 7 shows nucleic acid sequences and deduced amino acid sequences of the E. canis 28-kDa protein genes p28-5 (nucleotide 1-849: SEQ ID No. 3; amino acid sequence: SEQ ID No. 4) and p28-6 (nucleotide 1195-2031: SEQ ID No. 5; amino acid sequence: SEQ ID No. 6) including intergenic noncoding sequences (NC2, nucleotide 850-1194: SEQ ID No. 31). The ATG start codon and termination condons are shown in bold.

[0026]FIG. 8 shows schematic of the E. canis 28-kDa protein gene locus (5.592-Kb, containing five genes) indicating genomic orientation and intergenic noncoding regions (28NC1-4). The 28-kDa protein genes shown in Locus 1 and 2 (shaded) have been described (McBride et al., 1999; Reddy et al., 1998; Ohashi et al., 1998). The complete sequence of p28-5 and a new 28-kDa protein gene designated p28-6 was sequenced. The noncoding intergenic regions (28NC2-3) between p28-5, p28-6 and p28-7 were completed joining the previously unlinked loci 1 and 2.

[0027]FIG. 9 shows phylogenetic relatedness of the E. canis 28-kDa protein gene p28-4 (ECa28SA1), p28-5 (ECa28SA2), p28-6 (ECa28SA3), p28-7 (ECa28-1) and p28-8 (ECa28-2) based on amino acid sequences utilizing unbalanced tree construction. The length of each pair of branches represents the distance between amino acid pairs. The scale measures the distance between sequences.

[0028]FIG. 10 shows alignment of E. canis 28-kDa protein gene intergenic noncoding nucleic acid sequences (SEQ ID Nos. 30-33). Nucleic acids not shown, denoted with a dot (.), are identical to noncoding region 1 (28NC1). Divergence is shown with the corresponding one letter abbreviation. Gaps introduced for maximal alignment of the amino acid sequences are denoted with a dash (-). Putative transcriptional promoter regions (-10 and -35) and ribosomal binding site (RBS) are boxed.

[0029]FIG. 11 shows schematic representation of the nine gene E. canis p28 locus (10,677-bp) indicating genomic orientation and intergenic noncoding regions. The p28 genes (p28-1, 2, 3, 9) (unshaded) were identified in Example 8. Shaded p28 genes have been identified previously and designated as follows: p28-4, p30a (Ohashi et al., 1998b) and ORFI (Reddy et al., 1998); p28-5 and p28-6, (McBride, et. al., 2000); p28-7, p28 (McBride et al., 1999) and p30 (Ohashi et al., 1998b); and p28-8, p30-1 (Ohashi et al., 1998b).

[0030]FIG. 12 shows phylogenetic relationships of E. canis P28-1 to P28-9 based on the amino acid sequences. The length of each pair of branches represents the distance between amino acid pairs. The scale measures the percentage of divergence between the sequences.

[0031]FIG. 13 shows nucleic acid sequence (SEQ ID No. 39) and deduced amino acid sequence (SEQ ID No. 40) of E. canis p28-1 gene.

[0032]FIG. 14 shows nucleic acid sequence (SEQ ID No. 41) and deduced amino acid sequence (SEQ ID No. 42) of E. canis p28-2 gene.

[0033]FIG. 15 shows nucleic acid sequence (SEQ ID No. 43) and deduced amino acid sequence (SEQ ID No. 44) of E. canis p28-3 gene.

[0034]FIG. 16 shows nucleic acid sequence (SEQ ID No. 45) and deduced amino acid sequence (SEQ ID No. 46) of E. canis p28-9 gene.

DETAILED DESCRIPTION OF THE INVENTION

[0035] The present invention describes cloning, sequencing and expression of homologous genes encoding a 30-kilodalton (kDa) protein of Ehrlichia canis. A comparative molecular analysis of homologous genes among seven E. canis isolates and the E. chaffeensis omp-1 multigene family was also performed. Several new 28-kDa protein genes are identified as follows:

[0036] p28-7 (ECa28-1) has an 834-bp open reading frame encoding a protein of 278 amino acids (SEQ ID No. 2) with a predicted molecular mass of 30.5-kDa. An N-terminal signal sequence was identified suggesting that the protein is post-translationally modified to a mature protein of 27.7-kDa.

[0037] P28-6 (ECa28SA3) has an 840-bp open reading frame encoding a 280 amino acid protein (SEQ ID No. 6).

[0038] Using PCR to amplify 28-kDa protein genes of E. canis, a previously unsequenced region of p28-5 (Eca28SA2) was completed. Sequence analysis of p28-5 revealed an 849-bp open reading frame encoding a 283 amino acid protein (SEQ ID No. 4).

[0039] PCR amplification using primers specific for 28-kDa protein gene intergenic noncoding regions led to the sequencing of regions linkeding two previously separate loci, thereby identifying a single locus (5.592-kb) containing five 28-kDa protein genes (p28-4, -5, -6, -7 and -8). The five 28-kDa proteins were predicted to have signal peptides resulting in mature proteins, and had amino acid homology ranging from 51 to 72%. Analysis of intergenic regions revealed hypothetical promoter regions for each gene, suggesting that these genes may be independently and differentially expressed. Intergenic noncoding regions (28NC1-4) ranged in size from 299 to 355-bp, and were 48 to 71% homologous.

[0040] Furthermore, previously unknown regions of DNA upstream and downstream of the above five gene locus of tandemly arranged p28 genes were sequenced, and p28-1, -2, -3, and -9 were identified. Consequently, a nine gene E. canis p28 locus spanning 10, 677 bp was identified in the present invention.

[0041] The present invention is directed to, inter alia, homologous 28-kDa protein genes in Ehrlichia canis, p28-1, -2, -3, -6, -7, and p28-9, and a complete sequence of previously partially sequenced p28-5. Also disclosed is a multigene locus encoding nine homologous 28-kDa outer membrane proteins of Ehrlichia canis. Eight of the p28 genes were located on one DNA strand, and one p28 gene was found on the complementary strand. The nucleic acid homology among the nine p28 gene members was 37 to 75%, and the amino acid homology ranged from 28 to 72%.

[0042] In accordance with the present invention there may be employed conventional molecular biology, microbiology, and recombinant DNA techniques within the skill of the art. Such techniques are explained fully in the literature. See, e.g., Maniatis, Fritsch & Sambrook, “Molecular Cloning: A Laboratory Manual (1982); “DNA Cloning: A Practical Approach,” Volumes I and II (D. N. Glover ed. 1985); “Oligonucleotide Synthesis” (M. J. Gait ed. 1984); “Nucleic Acid Hybridization” [B. D. Hames & S. J. Higgins eds. (1985)]; “Transcription and Translation” [B. D. Hames & S. J. Higgins eds. (1984)]; “Animal Cell Culture” [R. I. Freshney, ed. (1986)]; “Immobilized Cells And Enzymes” [IRL Press, (1986)]; B. Perbal, “A Practical Guide To Molecular Cloning” (1984).

[0043] The invention includes a substantially pure DNA encoding a 28-kDa immunoreactive protein of Ehrlichia canis. The protein encoded by the DNA of this invention may share at least 80% sequence identity (preferably 85%, more preferably 90%, and most preferably 95%) with the amino acids listed in SEQ ID No. 2, 4, 6, 40, 42, 44 or 46. More preferably, the DNA includes the coding sequence of the nucleotides of SEQ ID No. 1, 3, 5, 39, 41, 43, 45, or a degenerate variant of such a sequence.

[0044] It is well known in the art that the amino acid sequence of a protein is determined by the nucleotide sequence of the DNA that encodes the protein. Because of the degeneracy of the genetic code (i.e., for most amino acids, more than one nucleotide triplet (codon) codes for a single amino acid), different nucleotide sequences can code for a particular amino acid, or polypeptide. Thus, the polynucleotide sequences of the subject invention also encompass those degenerate sequences that encode the polypeptides of the subject invention, or a fragment or variant thereof.

[0045] This invention also includes a substantially pure DNA containing a sequence of at least 15 consecutive nucleotides (preferably 20, more preferably 30, even more preferably 50, and most preferably all) of the region from the nucleotides listed in SEQ ID No 1, 3, 5, 39, 41, 43, or 45.

[0046] By “substantially pure DNA” is meant DNA that is not part of a milieu in which the DNA naturally occurs, by virtue of separation (partial or total purification) of some or all of the molecules of that milieu, or by virtue of alteration of sequences that flank the claimed DNA. The term therefore includes, for example, a recombinant DNA which is incorporated into a vector, into an autonomously replicating plasmid or virus, or into the genomic DNA of a prokaryote or eukaryote; or which exists as a separate molecule (e.g., a cDNA or a genomic or cDNA fragment produced by polymerase chain reaction (PCR) or restriction endonuclease digestion) independent of other sequences. It also includes a recombinant DNA which is part of a hybrid gene encoding an additional polypeptide sequence, e.g., a fusion protein. Also included in the present invention is a recombinant DNA which includes a portion of the nucleotides listed in SEQ ID No 1, 3, 5, 39, 41, 43, or 45 which encodes a 28-kDa immunoreactive protein of Ehrlichia canis.

[0047] The DNA should have at least about 70% sequence identity to the coding sequence of the nucleotides listed in SEQ ID No 1, 3, 5, 39, 41, 43, or 45, preferably at least 75% (e.g. at least 80%); and most preferably at least 90% identity. The identity between two sequences is a direct function of the number of matching or identical positions. When a subunit position in both of the two sequences is occupied by the same monomeric subunit, e.g., if a given position is occupied by an adenine in each of two DNA molecules, then they are identical at that position. For example, if 7 positions in a sequence 10 nucleotides in length are identical to the corresponding positions in a second 10-nucleotide sequence, then the two sequences have 70% sequence identity. The length of comparison sequences will generally be at least 50 nucleotides, preferably at least 60 nucleotides, more preferably at least 75 nucleotides, and most preferably 100 nucleotides. Sequence identity is typically measured using sequence analysis software (e.g., Sequence Analysis Software Package of the Genetics Computer Group, University of Wisconsin Biotechnology Center, 1710 University Avenue, Madison, Wis. 53705).

[0048] The present invention also comprises a vector comprising a DNA sequence coding for a which encodes a gene encoding a 28-kDa immunoreactive protein of Ehrlichia canis and said vector is capable of replication in a host which comprises, in operable linkage: a) an origin of replication; b) a promoter; and c) a DNA sequence coding for said protein. Preferably, the vector of the present invention contains a portion of the DNA sequence shown in SEQ ID No 1, 3, 5, 39, 41, 43, or 45.

[0049] A “vector” may be defined as a replicable nucleic acid construct, e.g., a plasmid or viral nucleic acid. Vectors may be used to amplify and/or express nucleic acid encoding a 28-kDa immunoreactive protein of Ehrlichia canis. An expression vector is a replicable construct in which a nucleic acid sequence encoding a polypeptide is operably linked to suitable control sequences capable of effecting expression of the polypeptide in a cell. The need for such control sequences will vary depending upon the cell selected and the transformation method chosen. Generally, control sequences include a transcriptional promoter and/or enhancer, suitable mRNA ribosomal binding sites, and sequences which control the termination of transcription and translation. Methods which are well known to those skilled in the art can be used to construct expression vectors containing appropriate transcriptional and translational control signals. See for example, the techniques described in Sambrook et al., 1989, Molecular Cloning: A Laboratory Manual (2nd Ed.), Cold Spring Harbor Press, N.Y. A gene and its transcription control sequences are defined as being “operably linked” if the transcription control sequences effectively control the transcription of the gene. Vectors of the invention include, but are not limited to, plasmid vectors and viral vectors. Preferred viral vectors of the invention are those derived from retroviruses, adenovirus, adeno-associated virus, SV40 virus, or herpes viruses.

[0050] In general, expression vectors containing promoter sequences which facilitate the efficient transcription of the inserted DNA fragment are used in connection with the host. As used herein, the term “host” is meant to include not only prokaryotes but also eukaryotes such as yeast, plant and animal cells. A recombinant DNA molecule or gene which encodes a 28-kDa immunoreactive protein of Ehrlichia canis of the present invention can be used to transform a host using any of the techniques commonly known to those of ordinary skill in the art. Especially preferred is the use of a vector containing coding sequences for a gene encoding a 28-kDa immunoreactive protein of Ehrlichia canis of the present invention for purposes of prokaryote transformation.

[0051] Prokaryotic hosts may include E. coli, S. tymphimurium, Serratia marcescens and Bacillus subtilis. Eukaryotic hosts include yeasts such as Pichia pastoris, mammalian cells and insect cells. The transformed hosts can be fermented and cultured according to means known in the art to achieve optimal cell growth.

[0052] As used herein, the term “engineered” or “recombinant” cell is intended to refer to a cell into which a recombinant gene, such as a gene encoding an Ehrlichia canis antigen has been introduced. Therefore, engineered cells are distinguishable from naturally occurring cells which do not contain a recombinantly introduced gene. Engineered cells are thus cells having a gene or genes introduced through the hand of man. Recombinantly introduced genes will either be in the form of a cDNA gene, a copy of a genomic gene, or will include genes positioned adjacent to a promoter not naturally associated with the particular introduced gene. In addition, the recombinant gene may be integrated into the host genome, or it may be contained in a vector, or in a bacterial genome transfected into the host cell.

[0053] The present invention is also drawn to substantially pure 28-30 kDa immunoreactive proteins of E. canis comprise of amino acid sequences listed in, for example, SEQ ID No. 2, 4, 6, 40, 42, 44, or 46.

[0054] By a “substantially pure protein” is meant a protein which has been separated from at least some of those components which naturally accompany it. Typically, the protein is substantially pure when it is at least 60%, by weight, free from the proteins and other naturally-occurring organic molecules with which it is naturally associated in vivo. Preferably, the purity of the preparation is at least 75%, more preferably at least 90%, and most preferably at least 99%, by weight. A substantially pure 28-kDa immunoreactive protein of Ehrlichia canis may be obtained, for example, by extraction from a natural source; by expression of a recombinant nucleic acid encoding a 28-kDa immunoreactive protein of Ehrlichia canis; or by chemically synthesizing the protein. Purity can be measured by any appropriate method, e.g., column chromatography such as immunoaffinity chromatography using an antibody specific for a 28-kDa immunoreactive protein of Ehrlichia canis, polyacrylamide gel electrophoresis, or HPLC analysis. A protein is substantially free of naturally associated components when it is separated from at least some of those contaminants which accompany it in its natural state. Thus, a protein which is chemically synthesized or produced in a cellular system different from the cell from which it naturally originates will be, by definition, substantially free from its naturally associated components. Accordingly, substantially pure proteins include eukaryotic proteins synthesized in E. coli, other prokaryotes, or any other organism in which they do not naturally occur.

[0055] In addition to substantially full-length proteins, the invention also includes fragments (e.g., antigenic fragments) of the 28-kDa immunoreactive protein of Ehrlichia canis (SEQ ID No. 2, 4, 6, 40, 42, 44, or 46). As used herein, “fragment,” as applied to a polypeptide, will ordinarily be at least 10 residues, more typically at least 20 residues, and preferably at least 30 (e.g., 50) residues in length, but less than the entire, intact sequence. Fragments of the 28-kDa immunoreactive protein of Ehrlichia canis can be generated by methods known to those skilled in the art, e.g., by enzymatic digestion of naturally occurring or recombinant 28-kDa immunoreactive protein of Ehrlichia canis, by recombinant DNA techniques using an expression vector that encodes a defined fragment of 28-kDa immunoreactive protein of Ehrlichia canis, or by chemical synthesis. The ability of a candidate fragment to exhibit a characteristic of 28-kDa immunoreactive protein of Ehrlichia canis (e.g., binding to an antibody specific for 28-kDa immunoreactive protein of Ehrlichia canis) can be assessed by methods described herein.

[0056] Purified 28-kDa immunoreactive protein of Ehrlichia canis or antigenic fragments of 28-kDa immunoreactive protein of Ehrlichia canis can be used to generate new antibodies or to test existing antibodies (e.g., as positive controls in a diagnostic assay) by employing standard protocols known to those skilled in the art.

[0057] As is well known in the art, a given polypeptide may vary in its immunogenicity. It is often necessary therefore to couple the immunogen (e.g., a polypeptide of the present invention) with a carrier. Exemplary and preferred carriers are keyhole limpet hemocyanin (KLH) and human serum albumin. Means for conjugating a polypeptide to a carrier protein are well known in the art and include glutaraldehyde, m-maleimidobenzoyl-N-hydroxysuccinimide ester, carbo-diimide and bis-biazotized benzidine. It is also understood that the peptide may be conjugated to a protein by genetic engineering techniques that are well known in the art.

[0058] As is also well known in the art, immunogenicity to a particular immunogen can be enhanced by the use of non-specific stimulators of the immune response known as adjuvants. Exemplary and preferred adjuvants include complete BCG, Detox, (RIBI, Immunochem Research Inc.) ISCOMS and aluminum hydroxide adjuvant (Superphos, Biosector).

[0059] Included in this invention are polyclonal antisera generated by using 28-kDa immunoreactive protein of Ehrlichia can is or a fragment of 28-kDa immunoreactive protein of Ehrlichia canis as the immunogen in, e.g., rabbits. Standard protocols for monoclonal and polyclonal antibody production known to those skilled in this art are employed. The monoclonal antibodies generated by this procedure can be screened for the ability to identify recombinant Ehrlichia canis cDNA clones, and to distinguish them from known cDNA clones.

[0060] The invention encompasses not only an intact monoclonal antibody, but also an immunologically-active antibody fragment, e.g., a Fab or (Fab)₂ fragment; an engineered single chain Fv molecule; or a chimeric molecule, e.g., an antibody which contains the binding specificity of one antibody, e.g., of murine origin, and the remaining portions of another antibody, e.g., of human origin.

[0061] In one embodiment, the antibody, or fragment thereof, may be linked to a toxin or to a detectable label, e.g. a radioactive label, non-radioactive isotopic label, fluorescent label, chemiluminescent label, paramagnetic label, enzyme label or calorimetric label. Those of ordinary skill in the art will know of these and other suitable labels which may be employed in accordance with the present invention. The binding of these labels to antibodies or fragments thereof can be accomplished using standard techniques commonly known to those of ordinary skill in the art.

[0062] It is also contemplated that pharmaceutical compositions may be prepared using the novel proteins of the present invention. In such a case, the pharmaceutical composition comprises the novel active composition(s) of the present invention and a pharmaceutically acceptable carrier. A person having ordinary skill in this art would readily be able to determine, without undue experimentation, the appropriate dosages and routes of administration of the active component of the present invention.

[0063] The phrase “pharmaceutically acceptable” refers to molecular entities and compositions that do not produce an allergic or similar untoward reaction when administered to a subject. The preparation of an aqueous composition that contains a protein as an active ingredient is well understood in the art. Typically, such compositions are prepared as injectables, either as liquid solutions or suspensions; solid forms suitable for solution in, or suspension in, liquid prior to injection can also be prepared. The preparation can also be emulsified.

[0064] A protein may be formulated into a composition in a neutral or salt form. Pharmaceutically acceptable salts, include the acid addition salts (formed with the free amino groups of the protein) and which are formed with inorganic acids such as, for example, hydrochloric or phosphoric acids, or such organic acids as acetic, oxalic, tartaric, mandelic, and the like. Salts formed with the free carboxyl groups can also be derived from inorganic bases such as, for example, sodium, potassium, ammonium, calcium, or ferric hydroxides, and such organic bases as isopropylamine, trimethylamine, histidine, procaine and the like.

[0065] Upon formulation, solutions will be administered in a manner compatible with the dosage formulation and in such amount as is therapeutically effective. The formulations are easily administered in a variety of dosage forms such as injectable solutions.

[0066] For parenteral administration in an aqueous solution, for example, the solution should be suitably buffered if necessary and the liquid diluent first rendered isotonic with sufficient saline or glucose. These particular aqueous solutions are especially suitable for intravenous, intramuscular, subcutaneous and intraperitoneal administration. In this connection, sterile aqueous media which can be employed will be known to those of skill in the art in light of the present disclosure. For example, one dosage could be dissolved in 1 mL of isotonic NaCl solution and either added to 1000 mL of hypodermoclysis fluid or injected at the proposed site of infusion, (see for example, “Remington's Pharmaceutical Sciences” 15 th Edition, pages 1035-1038 and 1570-1580). Some variation in dosage will necessarily occur depending on the condition of the subject being treated. The person responsible for administration will, in any event, determine the appropriate dose for the individual subject.

[0067] In one embodiment of the present invention, there are provided DNA sequences encoding a 30-kDa immunoreactive protein of Ehrlichia canis. Preferably, the protein has an amino acid sequence selected from the group consisting of SEQ ID No. 2, 4, 6, 40, 42, 44, 46, and the gene has a nucleic acid sequence selected from the group consisting of SEQ ID No. 1, 3, 5, 39, 41, 43, 45 and is a member of a polymorphic multiple gene family. More preferably, the protein has an N-terminal signal sequence which is cleaved after post-translational process resulting in the production of a mature 28-kDa protein. Still preferably, the DNAs encoding 28-kDa proteins are contained in a single multigene locus, which has the size of 10,677 bp and encodes nine homologous 28-kDa proteins of Ehrlichia canis.

[0068] In another embodiment of the present invention, there is provided an expression vector comprising a gene encoding a 28-kDa immunoreactive protein of Ehrlichia canis and capable of expressing the gene when the vector is introduced into a cell.

[0069] In still another embodiment of the present invention, there is provided a recombinant protein comprising an amino acid sequence selected from the group consisting of SEQ ID No. 2, 4, 6, 40, 42, 44, 46. Preferably, the amino acid sequence is encoded by a nucleic acid sequence selected from the group consisting of SEQ ID No. 1, 3, 5, 39, 41, 43, 45. More preferably, the recombinant protein comprises four variable regions which are surface exposed, hydrophilic and antigenic. Still preferably, the recombinant protein is an antigen.

[0070] In yet another embodiment of the present invention, there is provided a method of producing the recombinant protein, comprising the steps of obtaining a vector that comprises an expression region comprising a sequence encoding the amino acid sequence selected from the group consisting of SEQ ID No. 2, 4, 6, 40, 42, 44, 46 operatively linked to a promoter; transfecting the vector into a cell; and culturing the cell under conditions effective for expression of the expression region.

[0071] The invention may also be described in certain embodiments as a method of inhibiting Ehrlichia canis infection in a subject comprising the steps of: identifying a subject suspected of being exposed to or infected with Ehrlichia canis; and administering a composition comprising a 28-kDa antigen of Ehrlichia canis in an amount effective to inhibit an Ehrlichia canis infection. The inhibition may occur through any means such as, i.e. the stimulation of the subject's humoral or cellular immune responses, or by other means such as inhibiting the normal function of the 28-kDa antigen, or even competing with the antigen for interaction with some agent in the subject's body.

[0072] The following examples are given for the purpose of illustrating various embodiments of the invention and are not meant to limit the present invention in any fashion.

EXAMPLE 1 Sequencing Unknown 5′ and 3′ Regions of the ECa28-1 (p28-7) Gene

[0073] Ehrlichiae and Purification Ehrlichia canis (Florida strain and isolates Demon, D J, Jake, and Fuzzy) were provided by Dr. Edward Breitschwerdt, (College of Veterinary Medicine, North Carolina State University, Raleigh, N.C.). E. canis (Louisiana strain) was provided by Dr. Richard E. Corstvet (School of Veterinary Medicine, Louisiana State University, Baton Rouge, La.) and E. canis (Oklahoma strain) was provided by Dr. Jacqueline Dawson (Centers for Disease Control and Prevention, Atlanta, Ga.). Propagation of ehrlichiae was performed in DH82 cells with DMEM supplemented with 10% bovine calf serum and 2 mM L-glutamine at 37° C. The intracellular growth in DH82 cells was monitored by presence of E. canis morulae using general cytologic staining methods. Cells were harvested when 100% of the cells were infected with ehrlichiae and were then pelleted in a centrifuge at 17,000×g for 20 min. Cell pellets were disrupted with a Braun-Sonic 2000 sonicator twice at 40W for 30 sec on ice. Ehrlichiae were purified as described previously (Weiss et al., 1975). The lysate was loaded onto discontinuous gradients of 42%-36%-30% renografin, and centrifuged at 80,000×g for 1 hr. Heavy and light bands containing ehrlichiae were collected and washed with sucrose-phosphate-glutamate buffer (SPG, 218 mM sucrose, 3.8 mM KH₂PO₄, 7.2 mM K₂HPO₄, 4.9 mM glutamate, pH 7.0) and pelleted by centrifugation.

[0074] Nucleic Acid Preparation Ehrlichia canis genomic DNA was prepared by resuspending the renografin-purified ehrlichiae in 600 μg of 10 mM Tris-HCl buffer (pH 7.5) with 1% sodium dodecyl sulfate (SDS, w/v) and 100 ng/ml of proteinase K as described previously (McBride et al., 1996). This mixture was incubated for 1 hr at 56° C., and the nucleic acids were extracted twice with a mixture of phenol/chloroform/isoamyl alcohol (24:24:1). DNA was pelleted by absolute ethanol precipitation, washed once with 70% ethanol, dried and resuspended in 10 mM Tris (pH 7.5). Plasmid DNA was purified by using High Pure Plasmid Isolation Kit (Boehringer Mannheim, Indianapolis, Ind.), and PCR products were purified using a QIAquick PCR Purification Kit (Qiagen, Santa Clarita, Calif.).

[0075] Cloning of ECa28-1 (p28-7) Gene The full length sequence of p28-7 gene was determined using a Universal GenomeWalker Kit (CLONTECH, Palo Alto, Calif.) according to the protocol supplied by the manufacturer. Genomic E. canis (Jake isolate) DNA was digested completely with five restriction enzymes (DraI, EcoRV, PvuII, ScaI, Stul) which produce blunt-ended DNA. An adapter (AP1) supplied in the kit was ligated to each end of E. canis DNA. The genomic libraries were used as templates to find the unknown DNA sequence of the p28-7 gene by PCR using a primer complementary to a known portion of the p28-7 sequence and a primer specific for the adapter AP1. Primers specific for p28-7 used for genome walking were designed from the known DNA sequence derived from PCR amplification of p28-7 with primers 793 (SEQ ID NO. 16) and 1330 (SEQ ID NO. 17). Primers 394 (5′-GCATTTCCACAGGATCATAGGTAA-3′; nucleotides 687-710, SEQ ID NO. 21) and 394C (5′-TTACCTATGATCCTGT GGAAATGC-3; nucleotides 710-687, SEQ ID NO. 22) were used in conjunction with supplied primer AP1 to amplify the unknown 5′ and 3′ regions of the p28-7 gene by PCR. A PCR product corresponding to the 5′ region of the p28-7 gene amplified with primers 394C. and AP1 (2000-bp) was sequenced unidirectionally with primer 793C (5′-GAGTA ACCAACAGCTCCTGC-3′, SEQ ID No. 23). A PCR product corresponding to the 3′ region of the p28-7 gene amplified with primers 394 and AP1 (580-bp) was sequenced bidirectionally with the same primers. Noncoding regions on the 5′ and 3′ regions adjacent to the open reading frame were sequenced, and primers EC28OM-F (5′-TCTACTTTGCACTTCC ACTATTGT-3′, SEQ ID NO. 24) and EC28OM-R (5′-ATTCTTTTGCCACTATTT TTCTTT-3′, SEQ ID NO. 25) complementary to these regions were designed in order to amplify the entire p28-7 gene.

[0076] DNA Sequencing DNA was sequenced with an ABI Prism 377 DNA Sequencer (Perkin-Elmer Applied Biosystems, Foster City, Calif.). The entire p28-7 genes of seven E. canis isolates (four from North Carolina, and one each from Oklahoma, Florida, and Louisiana) were amplified by PCR with primers EC28OM-F (SEQ ID No. 24) and EC28OM-R (SEQ ID No. 25) with a thermal cycling profile of 95° C. for 5 minutes, and 30 cycles of 95° C. for 30 seconds, 62° C. for 1 minutes, and 72° C. for 2 minutes and a 72° C. extension for 10 minutes. The resulting PCR products were bidirectionally sequenced with the same primers.

EXAMPLE 2

[0077] PCR Amplification, Cloning, Sequencing and Expression E. canis ECa28-1 (p28-7) Gene

[0078] Expression Vectors The entire E. canis p28-7 gene was PCR-amplified with primers-EC28OM-F and EC28OM-R and cloned into pCR2.1-TOPO TA cloning vector to obtain the desired set of restriction enzyme cleavage sites (Invitrogen, Carlsbad, Calif.). The insert was excised from pCR2.1-TOPO with BstX 1 and ligated into pcDNA 3.1 eukaryotic expression vector (Invitrogen, Carlsbad, Calif.) designated pcDNA3.1/EC28 for subsequent studies. The pcDNA3.1/EC28 plasmid was amplified, and the gene was excised with a KpnI-XbaI double digestion and directionally ligated into pThioHis prokaryotic expression vector (Invitrogen, Carlsbad, Calif.). The clone (designated pThioHis/EC28) produced a recombinant thioredoxin fusion protein in Escherichia coli BL21. The recombinant fusion protein was crudely purified in the insoluble phase by centrifugation. The control thioredoxin fusion protein was purified from soluble cell lysates under native conditions using nickel-NTA spin columns (Qiagen, Santa Clarita, Calif.).

[0079] Western Blot Analysis Recombinant E. canis p28-7 fusion protein was subjected to SDS-polyacrylamide gel electrophoresis (SDS-PAGE) on 4-15% Tris-HCl gradient gels (Bio-Rad, Hercules, Calif.) and transferred to pure nitrocellulose (Schleicher & Schuell, Keene, N.H.) using a semi-dry transfer cell (Bio-Rad, Hercules, Calif.). The membrane was incubated with convalescent phase antisera from an E. canis-infected dog diluted 1:5000 for 1 hour, washed, and then incubated with an anti-canine IgG (H & L) alkaline phosphatase-conjugated affinity-purified secondary antibody at 1:1000 for 1 hour (Kirkegaard & Perry Laboratories, Gaithersburg, Md.). Bound antibody was visualized with 5-bromo-4-chloro-3-indolyl phosphate/nitroblue tetrazolium (BCIP/NBT) substrate (Kirkegaard & Perry Laboratories, Gaithersburg, Md.).

[0080] Southern Blot Analysis To determine if multiple genes homologous to the p28-7 gene were present in the E. canis genome, a genomic Southern blot analysis was performed using a standard procedure (Sambrook et al. 1989). E. canis genomic DNA digested completely with each of the restriction enzymes BanII, EcoRV, HaeII, KpnI and SpeI, which do not cut within the p28-7 gene, and AseI which digests p28-7 at nucleotides 34, 43 and 656. The probe was produced by PCR amplification with primers EC280M-F and EC28OM-R and digoxigenin (DIG)-labeled deoxynucleotide triphosphates (dNTPs) (Boehringer Mannheim, Indianapolis, Ind.) and digested with AseI. The digested probe (566-bp) was separated by agarose gel electrophoresis, gel-purified and then used for hybridization. The completely digested genomic E. canis DNA was electrophoresed and transferred to a nylon membrane (Boehringer Mannheim, Indianapolis, Ind.) and hybridized at 40° C. for 16 hr with the p28-7 gene DIG-labeled probe in DIG Easy Hyb buffer according to the manufacturer's protocol (Boehringer Mannheim, Indianapolis, Ind.). Bound probe was detected with a anti-DIG alkaline phosphatase-conjugated antibody and a luminescent substrate (Boehringer Mannheim, Indianapolis, Ind.) and exposed to BioMax scientific imaging film (Eastman Kodak, Rochester, N.Y.).

[0081] Sequence Analysis and Comparasion E. chaffeensis p28 and C. ruminantium map-1 DNA sequences were obtained from the National Center of Biotechnology Information (NCBI). Nucleotide and deduced amino acid sequences, and protein and phylogenetic analyses were performed with LASERGENE software (DNASTAR, Inc., Madison, Wis.). Analysis of post-translational processing was performed by the method of McGeoch and von Heijne for signal sequence recognition using the PSORT program (McGeoch, 1985; von Heijne, 1986)

[0082] Sequence analysis of p28-7 from seven different strains of E. canis was performed with primers designed to amplify the entire gene. Analysis revealed the sequence of this gene was conserved among the isolates from North Carolina (four), Louisiana, Florida and Oklahoma.

[0083] Results

[0084] Alignment of nucleic acid sequences from E. chaffeensis p28 and Cowdria ruminantium map-1 using the Jotun-Hein aligorithm produced a consensus sequence with regions of high homology (>90%). These homologous regions (nucleotides 313-332 and 823-843 of C. ruminantium map-1; 307-326 and 814-834 of E. chaffeensis p28) were targeted as primer annealing sites for PCR amplification. PCR amplification of the E. canis p28-7 gene was accomplished with primers 793 (5-GCAGGAGCTGTTGGTTACTC-3′) (SEQ ID NO. 16) and 1330 (5′-CCTTCCTCCAAGTTCTATGCC-3′) (SEQ ID NO. 17), resulting in a 518-bp PCR product. E. canis DNA was amplified with primers 793 and 1330 with a thermal cycling profile of 95° C. for 2 min, and 30 cycles of 95° C. for 30 sec, 62° C. for 1 min, 72° C. for 2 min followed by a 72° C. extension for 10 min and 4° C. hold. The nucleic acid sequence of the E. canis PCR product was obtained by sequencing the product directly with primers 793 and 1330.

[0085] Analysis of the sequence revealed an open reading frame encoding a protein of 170 amino acids, and alignment of the 518-bp sequence obtained from PCR amplification of E. canis with the DNA sequence of E. chaffeensis p28 gene revealed a similarity greater than 70%, indicating that the genes were homologous.

[0086] Adapter PCR with primers 394 and 793C was performed to determine the 5′ and 3′ segments of the sequence of the entire gene. Primer 394 produced four PCR products (3-kb, 2-kb, 1-kb, and 0.8-kb), and the 0.8-bp product was sequenced bidirectionally using primers 394 and AP1. The deduced sequence overlapped with the 3′ end of the 518-bp product, extending the open reading frame 12-bp to a termination codon. An additional 625-bp of non-coding sequence at the 3′ end of the p28-7 gene was also sequenced.

[0087] Primer 394C was used to amplify the 5′ end of the p28-7 gene with supplied primer API. Amplification with these primers resulted in three PCR products (3.3, 3-kb, and 2-kb). The 2-kb fragment was sequenced unidirectionally with primer 793C. The sequence provided the putative start codon of the p28-7 gene and completed the 834-bp open reading frame encoding a protein of 278 amino acids. An additional 144-bp of readable sequence in the 5′ noncoding region of the p28-7 gene was generated. Primers EC28OM-F and EC28OM-R were designed from complementary non-coding regions adjacent to the p28-7 gene.

[0088] The PCR product amplified with these primers was sequenced directly with the same primers. The complete DNA sequence for the E. canis p28-7 gene (SEQ ID NO. 1) is shown in FIG. 1. The p28-7 PCR fragment amplified with these primers contained the entire open reading frame and 17 additional amino acids from the 5′ non-coding primer region. The gene was directionally subcloned into pThioHis expression vector, and E. coli (BL21) were transformed with this construct. The expressed p28-7-thioredoxin fusion protein was insoluble. The expressed protein had an additional 114 amino acids associated with the thioredoxin, 5 amino acids for the enterokinase recognition site, and 32 amino acids from the multiple cloning site and 5′ non-coding primer region at the N-terminus. Convalescent-phase antiserum from an E. canis infected dog recognized the expressed recombinant fusion protein, but did not react with the thioredoxin control (FIG. 2).

EXAMPLE 3

[0089] Sequence Homology of E. canis p28-7 Gene

[0090] The nucleic acid sequence of E. canis p28-7 (834-bp) and the E. chaffeensis omp-1 family of genes including signal sequences (p28-7, omp-1A, B, C, D, E, and F) were aligned using the Clustal method to examine homology between these genes (alignment not shown). Nucleic acid homology was equally conserved (68.9%) between E. canis p28-7, E. chaffeensis p28 and omp-1F. Other putative outer membrane protein genes in the E. chaffeensis omp-1 family, omp-1D (68.2%), omp-1E (66.7%), omp-1C (64.1%), Cowdria ruminantium map-1 (61.8%), E. canis 28-kDa protein 1 gene (60%) and 28-kDa protein 2 gene (partial) (59.5%) were also homologous to p28-7. E. chaffeensis omp-1B had the least nucleic acid homology (45.1%) with E. canis p28-7.

[0091] Alignment of the predicted amino acid sequences of E. canis P28-7 (SEQ ID NO. 2) and E. chaffeensis P28 revealed amino acid substitutions resulting in four variable regions (VR). Substitutions or deletions in the amino acid sequence and the locations of variable regions of E. canis P28-7 and the E. chaffeensis OMP-1 family were identified (FIG. 3). Amino acid comparison including the signal peptide revealed that E. canis P28-7 shared the most homology with OMP-1F (68%) of the E. chaffeensis OMP-1 family, followed by E. chaffeensis P28 (65.5%), OMP-1E (65.1%), OMP-1D (62.9%), OMP-1C (62.9%), Cowdria ruminantium MAP-1 (59.4%), E. canis 28-kDa protein 1 (55.6%) and 28-kDa protein 2 (partial) (53.6%), and OMP-1B (43.2%). The phylogenetic relationships based on amino acid sequences show that E. canis P28-7 and C. ruminantium MAP-1, E. chaffeensis OMP-1 proteins, and E. canis 28-kDa proteins 1 and 2 (partial) are related (FIG. 4).

EXAMPLE 4

[0092] Predicted Surface Probability and Immunoreactivity of E. canis P28-7

[0093] Analysis of E. canis P28-7 using hydropathy and hydrophilicity profiles predicted surface-exposed regions on P28-7 (FIG. 6). Eight major surface-exposed regions consisting of 3 to 9 amino acids were identified on E. canis P28-7 and were similar to the profile of surface-exposed regions on E. chaffeensis P28 (FIG. 6). Five of the larger surface-exposed regions on E. canis P28-7 were located in the N-terminal region of the protein. Surface-exposed hydrophilic regions were found in all four of the variable regions of E. canis P28-7. Ten T-cell motifs were predicted in the P28-7 using the Rothbard-Taylor aligorithm (Rothbard and Taylor, 1988), and high antigenicity of the E. canis P28-7 was predicted by the Jameson-Wolf antigenicity aligorithm (FIG. 6) (Jameson and Wolf, 1988). Similarities in antigenicity and T-cell motifs were observed between E. canis P28-7 and E. chaffeensis P28.

EXAMPLE 5

[0094] Detection of Homologous Genomic Copies of E. canis p28-7 Gene

[0095] Genomic Southern blot analysis of E. canis DNA completely digested independently with restriction enzymes BanII, EcoRV, HaeII, KpnI, SpeI, which do not have restriction endonuclease sites in the p28-7 gene, and AseI, which has internal restriction endonuclease sites at nucleotides 34, 43 and 656, revealed the presence of at least three homologous p28-7 gene copies (FIG. 5). Although E. canis p28-7 has internal Ase I internal restriction sites, the DIG-labeled probe used in the hybridization experiment targeted a region of the gene within a single DNA fragment generated by the AseI digestion of the gene. Digestion with AseI produced 3 bands (approximately 566-bp, 850-bp, and 3-kb) that hybridized with the p28-7 DNA probe indicating the presence of multiple genes homologous to p28-7 in the genome. Digestion with EcoRV and SpeI produced two bands that hybridized with the p28-7 gene probe.

EXAMPLE 6

[0096] PCR Amplification of E. canis ECa28SA2 (p28-5), ECa28SA3 (p28-6) Genes and Identification of the Multiple Gene Locus

[0097] In order to specifically amplify possible unknown genes downstream of ECa28SA2 (p28-5), primer 46f specific for p28-5 (5′-ATATACTTCCTACCTAATGTCTCA-3′, SEQ ID No. 18), and primer 1330 (SEQ ID No. 17) which targets a conserved region on the 3′ end of p28-7 gene were used for amplification. The amplified product was gel purified and cloned into a TA cloning vector (Invitrogen, Santa Clarita, Calif.). The clone was sequenced bidirectionally with primers: M13 reverse from the vector, 46f, ECa28SA2 (5′-AGTGCAGAGTCTTCGGTTTC-3′, SEQ ID No. 19), ECa5.3 (5′-GTTACTTGCGGAGGACAT-3′, SEQ ID No. 20). DNA was amplified with a thermal cycling profile of 95° C. for 2 min, and 30 cycles of 95° C. for 30 sec, 48° C. for 1 min, 72° C. for 1 min followed by a 72° C. extension for 10 min and 4° C. hold.

[0098] A 2-kb PCR product was amplified with these primers that contained 2 open reading frames. The first open reading frame contained the known region of the p28-5 gene and a previously unsequenced 3′ portion of the gene. Downstream from p28-5 an additional non identical, but homologous 28-kDa protein gene was found, and designated ECa28SA3 (p28-6).

[0099] Specific primers designated ECaSA3-2 (5′-CTAGGATTA GGTTATAGTATAAGTT-3′, SEQ ID No. 26) corresponding to regions within p28-6 and primer 793C (SEQ ID No. 23) which anneals to a region with p28-7 were used to amplify the intergenic region between gene p28-6 and p28-7. DNA was amplified with a thermal cycling profile of 95° C. for 2 min, and 30 cycles of 95° C. for 30 sec, 50° C. for 1 min, 72° C. for 1 min followed by a 72° C. extension for 10 min and 4° C. hold.

[0100] An 800-bp PCR product was amplified which contained the 3′ end of p28-6, the intergenic region between p28-6 and p28-7 (28NC3) and the 5′ end of p28-7, joining the previously separate loci (FIG. 8). The 849-bp open reading frame of p28-5 encodes a 283 amino acid protein, and p28-6 has an 840-bp open reading frame encoding a 280 amino acid protein. The intergenic noncoding region between p28-6 and p28-7 was 345-bp in length (FIGS. 7 and 8)

EXAMPLE 7

[0101] Nucleic and Amino Acid Homology of E. canis p28-4, p28-5, p28-6, p28-7 and p28-8 Proteins

[0102] The nucleic and amino acid sequences of all five E. canis 28-kDa protein genes were aligned using the Clustal method to examine the homology between these genes. The nucleic acid homology ranged from 58 to 75% and a similar amino acid homology of ranging from 67 to 72% was observed between the E. canis 28-kDa protein gene members (FIG. 9).

[0103] Transcriptional Promoter Regions The intergenic regions between the 28-kDa protein genes were analyzed for promoter sequences by comparison with consensus Escherichia coli promoter regions and a promoter from E. chaffeensis (Yu et al., 1997; McClure, 1985). Putative promoter sequences including RBS, -10 and -35 regions were identified in 4 intergenic sequences corresponding to genes p28-5, p28-6, p28-7, and p28-8 (ECa28-2) (FIG. 10). The upstream noncoding region of p28-4 (ECa28SA1) is not known and was not analyzed.

[0104] N-Terminal Signal Sequence The amino acid sequence analysis revealed that entire E.canis p28-7 has a deduced molecular mass of 30.5-kDa and the entire p28-6 has a deduced molecular mass of 30.7-kDa. Both proteins have a predicted N-terminal signal peptide of 23 amino acids (MNCKKILITTALMSLMYYAPSIS, SEQ ID No. 27), which is similar to that predicted for E. chaffeensis P28 (MNYKKILTSALISLISSLPGV SFS, SEQ ID NO. 28), and the OMP-1 protein family (Yu et al., 1999a; Ohashi et al., 1998b).

[0105] A preferred cleavage site for signal peptidases (SIS; Ser-X-Ser) (Oliver, 1985) is found at amino acids 21, 22, and 23 of p28-7. An additional putative cleavage site at amino acid position 25 (MNCKKILITALISLMYSIPSISSFS, SEQ ID NO. 29) identical to the predicted cleavage site of E. chaffeensis P28 (SFS) was also present, and would result in a mature p28-7 with a predicted molecular mass of 27.7-kDa. Signal cleavage site of the previously reported partial sequence of p28-5 is predicted at amino acid 30. However, signal sequence analysis predicted that p28-4 had an uncleavable signal sequence.

SUMMARY

[0106] Proteins of similar molecular mass have been identified and cloned from multiple rickettsial agents including E. canis, E. chaffeensis, and C. ruminantium (Reddy et al., 1998; Jongejan et al., 1993; Ohashi et al., 1998). A single locus in Ehrlichia chaffeensis with 6 homologous p28 genes, and 2 loci in E. canis, each containing some homologous 28-kDa protein genes have been previously described.

[0107] The present invention demonstrated the cloning, expression and characterization of genes encoding mature 28-kDa proteins of E. canis that are homologous to the omp-1 multiple gene family of E. chaffeensis and the C. ruminantium map-1 gene. Two new 28-kDa protein genes were identified, p28-7 and p28-6. Another E.canis 28-kDa protein gene, p28-5, partially sequenced previously (Reddy et al., 1998), was sequenced completely in the present invention. Also disclosed is the identification and characterization of a single locus in E.canis containing five E.canis 28-kDa protein genes (p28-4, p28-5, p28-6, p28-7 and p28-8).

[0108] The E.canis 28-kDa proteins are homologous to E.chaffeensis OMP-1 family and the MAP-1 protein of C. rumanintium. The most homologous E. canis 28-kDa proteins (p28-6, p28-7 and p28-8) are sequentially arranged in the locus. Homology of these proteins ranged from 67.5% to 72.3%. Divergence among these 28-kDa proteins was 27.3% to 38.6%. E. canis 28-kDa proteins p28-4 and p28-5 were the least homologous with homology ranging from 50.9% to 59.4% and divergence of 53.3 to 69.9%. Differences between the genes lies primarily in the four hypervariable regions and suggests that these regions are surface exposed and subject to selective pressure by the immune system. Conservation of p28-7 among seven E. canis isolates has been reported (McBride et al., 1999), suggesting that E.canis may be clonal in North America. Conversely, significant diversity of p28 among E. chaffeensis isolates has been reported (Yu et al., 1999a).

[0109] All of the E. canis 28-kDa proteins appear to be post translationally processed from a 30-kD protein to a mature 28-kD protein. Recently, a signal sequence was identified on E. chaffeensis P28 (Yu et al., 1999a), and N-terminal amino acid sequencing has verified that the protein is post-translationally processed resulting in cleavage of the signal sequence to produce a mature protein (Ohashi et al., 1998). The leader sequences of OMP-1F and OMP-1E have also been proposed as leader signal peptides (Ohashi et al., 1998). Signal sequences identified on E. chaffeensis OMP-1F, OMP-1E and P28 are homologous to the leader sequence of E. canis 28-kDa protein. Promoter sequences for the p28 genes have not been determined experimentally, but putative promoter regions were identified by comparison with consensus sequences of the RBS, -10 and -35 promoter regions of E. coli and other ehrlichiae (Yu et al., 1997; McClure, 1985). Such promoter sequences would allow each gene to potentially be transcribed and translated, suggesting that these genes may be differentially expressed in the host. Persistence of infection in dogs may be related to differential expression of p28 genes resulting in antigenic changes in vivo, thus allowing the organism to evade the immune response.

[0110] The E. canis 28-kda protein genes were found to exhibit nucleic acid and amino acid sequence homology with the E. chaffeensis omp-1 gene family and C. ruminantium map-1 gene. Previous studies have identified a 30-kDa protein of E. canis that reacts with convalescent phase antisera against E. chaffeensis, but was believed to be antigenically distinct (Rikihisa et al., 1994). Findings based on comparison of amino acid substitutions in four variable regions of E. canis 28-kDa proteins support this possibility. Together these findings also suggest that the amino acids responsible for the antigenic differences between E. canis and E. chaffeensis P28 are located in these variable regions and are readily accessible to the immune system.

[0111] It was reported that immunoreactive peptides were located in the variable regions of the 28-kDa proteins of C. ruminantium, E. chaffeensis and E. canis (Reddy et al., 1998). Analysis of E. canis and E. chaffeensis P28 revealed that all of the variable regions have predicted surface-exposed amino acids. A study in dogs demonstrated lack of cross protection between E. canis and E. chaffeensis (Dawson and Ewing, 1992). This observation may be related to antigenic differences in the variable regions of P28 as well as in other immunologically important antigens of these ehrlichial species. Another study found that convalescent phase human antisera from E. chaffeensis-infected patients recognized 29/28-kDa protein(s) of E. chaffeensis and also reacted with homologous proteins of E. canis (Chen et al., 1997). Homologous and crossreactive epitopes on the E. canis 28-kDa protein and E. chaffeensis P28 appear to be recognized by the immune system.

[0112]E. canis 28-kDa proteins may be important immunoprotective antigens. Several reports have demonstrated that the 30-kDa antigen of E. canis exhibits strong immunoreactivity (Rikihisa et al., 1994; Rikihisa et al., 1992). Antibodies in convalescent phase antisera from humans and dogs have consistently reacted with proteins in this size range from E. chaffeensis and E. canis, suggesting that they may be important immunoprotective antigens (Rikihisa et al., 1994; Chen et al., 1994; Chen et al., 1997). In addition, antibodies to 30, 24 and 21-kDa proteins developed early in the immune response to E. canis (Rikihisa et al., 1994; Rikihisa et al., 1992), suggesting that these proteins may be especially important in the immune responses in the acute stage of disease. Recently, a family of homologous genes encoding outer membrane proteins with molecular masses of 28-kDa have been identified in E. chaffeensis, and mice immunized with recombinant E. chaffeensis P28 appeared to have developed immunity against homologous challenge (Ohashi et al., 1998). The P28 of E. chaffeensis has been demonstrated to be present in the outer membrane, and immunoelectron microscopy has localized the P28 on the surface on the organism, and thus suggesting that it may serve as an adhesin (Ohashi et al., 1998). It is likely that the 28-kDa proteins of E. canis identified in this study have the same location and possibly serve a similar function.

[0113] Comparison of p28-7 from different strains of E. canis revealed that the gene is apparently completely conserved. Studies involving E. chaffeensis have demonstrated immunologic and molecular evidence of diversity. Patients infected with E. chaffeensis have variable immunoreactivity to the 29/28-kDa proteins, suggesting that there is antigenic diversity (Chen et al., 1997). Recently molecular evidence has been generated to support antigenic diversity in the p28 gene from E. chaffeensis (Yu et al., 1999a). A comparison of five E. chaffeensis isolates revealed that two isolates (Sapulpa and St. Vincent) were 100% identical, but three others (Arkansas, Jax, 91HE17) were divergent by as much as 13.4% at the amino acid level. The conservation of E. canis p28-7 suggests that E. canis strains found in the United States may be genetically identical, and thus E. canis 28-kDa protein is an attractive vaccine candidate for canine ehrlichiosis in the United States. Further analysis of E. canis isolates outside the United States may provide information regarding the origin and evolution of E. canis. Conservation of the 28-kDa protein makes it an important potential candidate for reliable serodiagnosis of canine ehrlichiosis.

[0114] The role of multiple homologous genes is not known at this point; however, persistence of E.canis infections in dogs could conceivably be related to antigenic variation due to variable expression of homologous 28-kDa protein genes, thus enabling E. canis to evade immune surveillance. Variation of msp-3 genes in A. marginale is partially responsible for variation in the MSP-3 protein, resulting in persistent infections (Alleman et al., 1997). Studies to examine 28-kDa protein gene expression by E. canis in acutely and chronically infected dogs would provide insight into the role of the 28-kDa protein gene family in persistence of infection.

EXAMPLE 8

[0115] Identification of E. canis p28-1, p28-2, p28-3 and p28-9 Genes

[0116] Unknown regions of DNA upstream and downstream of the five gene locus of tandemly arranged p28 genes described above were sequenced by designing gene specific primers for p28-1 (ECa28-75C) and p28-5 (ECa28-5-818f) to extend the p28 gene locus bidirectionally. Multiple gene walks were performed to obtain the unknown sequence as follows: 1.9-kp downstream of the 5 gene locus was amplified and sequenced using primers p28-5-818f (5′-TTA AAC ATA TGC CAC TTC GGA CTA-3′, SEQ ID No. 34), producing a 900-bp amplicon, and 1191 (5′-TAT GAT CGT GTA AAA TTG CTG TGA GTA T-3′, SEQ ID No. 35), producing a 1-kb amplicon. The 3.67-kbp of DNA upstream of the five gene locus was amplified and sequenced with primers ECa28-75C (5′-TAC TGG CAC GTG CTG GAC TA-3′, SEQ ID No. 36), producing a 1.6-kbp amplicon; ECa5′-1600 (5′-CAC CAA TAA ATG CAG AGA CTT C-3′, SEQ ID No. 37), producing a 1.6-kbp amplicon; and 3125 (5′-AAT CCA TCA TTT CTC ATT ACA GTG TG-3′, SEQ ID No. 38), producing a 800-bp amplicon. The locus of nine tandemly arranged genes consisting of the four new p28 genes, and the five p28 genes described above were designated p28-1 through p28-9 (FIG. 11).

[0117] The nucleic acid and amino acid sequences of the E. canis p28 genes were aligned using the Clustal method to examine the homology between these genes. Homology of these proteins ranged from 67.5% to 75%, and divergence among these P28 proteins was 26.9% to 38%. E. canis P28 proteins P28-1, P28-2, and P28-9 were the least homologous with the other p28 genes ranging from 37% to 49% and divergence of 53 to 77%. The nucleic acid homology of the nine p28 genes ranged from 28 to 72%. The phylogenetic relationships based on the E. canis p28 amino acid sequences are shown in FIG. 12.

[0118] Nucleotide sequence and accession numbers. The GenBank accession numbers for the nucleic acid and amino acid sequences for the complete nine gene E. canis (Jake strain) p28 gene locus is AF082744. This accession number was originally assigned to p28-7, but has been updated with the sequence of the nine gene p28 locus, which includes p28-7. GenBank accession numbers for nucleic acid and amino acid sequences of p28-7 in other E. canis isolates described in this study are: Louisiana, AF082745; Oklahoma, AF082746; Demon, AF082747; DJ, AF082748; Fuzzy, AF082749; Florida, AF082750.

[0119] Multiple bands in the 28-kilodalton range have been observed by immunoblots of convalescent sera from E. canis infected dogs (Rikihisa et al., 1994), and expression of multiple p28 proteins could be an explanation for this observation. Southern blot studies suggest that other p28 genes, in addition to the five members of this locus, are present in the genome (McBride et al., 1999; Ohashi et al., 1998b).

[0120] In this study a single gene locus containing nine tandemly arranged E. canis p28 genes encoding homologous, but nonidentical, p28 genes was identified. The nine gene locus included four new p28 genes (FIGS. 13-16) and five tandemly arranged p28 genes that were reported above. Eight of the p28 genes were located on one DNA strand, and one p28 gene was found on the complementary strand. The nucleic acid homology among the nine p28 gene members was 37 to 75%, and the amino acid homology ranged from 28 to 72%:

[0121] The P28s of E. canis were found to be as closely related to 28-kilodalton proteins of other species such as E. chaffeensis as they are to themselves (McBride et al., 2000). Differences among the proteins are found primarily in several major hypervariable regions and suggest that these regions are surface exposed and subject to selective pressure by the immune system (McBride et al., 2000).

[0122] Conservation of an E. canis p28 gene (p28-7) among seven geographically different isolates has been reported (McBride et al., 1999), suggesting that E.canis may be highly conserved in North America. Similarly, the 120-kDa glycoprotein of E. canis is also conserved among isolates in the United States (Yu et al., 1997). In contrast, both the 120-kDa and the 28-kDa protein genes of E. chaffeensis are divergent among isolates (Yu et al., 1999a; Chen et al., 1997). The diversity of the 28-kDa protein gene of E. chaffeensis appeared to result from point mutations in the hypervariable regions perhaps due to selective immune pressure (Yu et al., 1999a). These data suggest that E. canis may have been introduced into North America relatively recently, and this may account for the conservation that was observed among isolates. The conservation of p28 genes in E. canis isolates may provide an opportunity to develop vaccine and serodiagnostic antigens that are particularly effective for disease prevention and serodiagnosis. A mixture of the P28s may provide the most reliable serodiagnostic test, but serodiagnosis with a single P28 has been reported to be useful for immunodiagnosis (Ohashi et al., 1998b; McBride et al., 1999).

[0123] The following references were cited herein.

[0124] Alleman A. R., et al., (1997) Infect Immun 65: 156-163.

[0125] Anderson B. E., et al., (1991) J Clin Microbiol 29: 2838-2842.

[0126] Anderson B. E., et al., (1992) Int J Syst Bacteriol 42: 299-302.

[0127] Brouqui P., et al., (1992) J Clin Microbiol 30: 1062-1066.

[0128] Chen S. M., et al., (1997) Clin Diag Lab Immunol 4: 731-735.

[0129] Chen S. M., et al., (1994) Am J Trop Med Hyg 50: 52-58.

[0130] Dawson J. E., et al., (1992) Am J Vet Res 53: 1322-1327.

[0131] Dawson J. E., et al., (1991) J Infect Dis 163: 564-567.

[0132] Donatien, et al., (1935) Bull Soc Pathol Exot 28: 418-9.

[0133] Ewing, (1963) J Am Vet Med Assoc 143: 503-6.

[0134] Groves M. G., et al., (1975) Am J Vet Res 36: 937-940.

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[0137] Jongejan F., et al., (1993) Rev Elev Med Vet Pays Trop 46: 145-152.

[0138] McBride J. W., et al., (1996) J Vet Diag Invest 8: 441-447.

[0139] McBride, et al.,. (1999) Clin Diagn Lab Immunol. 6: 392-399.

[0140] McBride, et al.,. (2000) Gene; In press

[0141] McClure, (1985) Ann Rev Biochem 54: 171-204.

[0142] McGeoch D. J. (1985) Virus Res 3: 271-286.

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[0144] Nyindo, et al., (1971) Am J Vet Res 32: 1651-58.

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[0146] Ohashi, et al., (1998b) J Clin Microb 36: 2671-80

[0147] Reddy, et al., (1998) Biochem Biophys Res Comm 247: 636-43.

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[0149] Rothbard J. B., et al., (1988) The EMBO J7: 93-100.

[0150] Sambrook J., et al., (1989) In Molecular Cloning: A Laboratory Manual. Cold Spring Harbor: Cold Spring Harbor Press.

[0151] Sulsona et al., (1999) Biochem. Biophys. Res. Commun. 257: 300-305.

[0152] Troy G. C., et al., (1990) Canine ehrlichiosis. In Infectious diseases of the dog and cat. Green C. E. (ed). Philidelphia: W. B. Sauders Co.

[0153] von Heijne, (1986) Nucl Acids Res 14: 4683-90.

[0154] Walker, et al., (1970) J Am Vet Med Assoc 157: 43-55.

[0155] Weiss E., et al., (1975) Appl Microbiol 30: 456-463.

[0156] Yu et al., (1993) J. Clin. Microbiol. 31: 3284-3288.

[0157] Yu, et al., (1997) Gene 184: 149-154.

[0158] Yu, et al., (1999a) J. Clin. Microbiol. 37: 1137-1143.

[0159] Yu et al., (2000) Gene 248: 59-68.

[0160] Any patents or publications mentioned in this specification are indicative of the levels of those skilled in the art to which the invention pertains. These patents and publications are herein incorporated by reference to the same extent as if each individual publication was individually indicated to be incorporated by reference.

[0161] One skilled in the art will readily appreciate that the present invention is well adapted to carry out the objects and obtain the ends and advantages mentioned, as well as those inherent therein. The present examples along with the methods, procedures, treatments, molecules, and specific compounds described herein are presently representative of preferred embodiments, are exemplary, and are not intended as limitations on the scope of the invention. Changes therein and other uses will occur to those skilled in the art which are encompassed within the spirit of the invention as defined by the scope of the claims.

1 46 1 1607 DNA Ehrlichia canis nucleic acid sequence of E. canis p28-7 1 attttattta ttaccaatct tatataatat attaaatttc tcttacaaaa atctctaatg 60 ttttatacct aatatatata ttctggcttg tatctacttt gcacttccac tattgttaat 120 ttattttcac tattttaggt gtaatatgaa ttgcaaaaaa attcttataa caactgcatt 180 aatatcatta atgtactcta ttccaagcat atctttttct gatactatac aagatggtaa 240 catgggtggt aacttctata ttagtggaaa gtatgtacca agtgtctcac attttggtag 300 cttctcagct aaagaagaaa gcaaatcaac tgttggagtt tttggattaa aacatgattg 360 ggatggaagt ccaatactta agaataaaca cgctgacttt actgttccaa actattcgtt 420 cagatacgag aacaatccat ttctagggtt tgcaggagct atcggttact caatgggtgg 480 cccaagaata gaattcgaaa tatcttatga agcattcgac gtaaaaagtc ctaatatcaa 540 ttatcaaaat gacgcgcaca ggtactgcgc tctatctcat cacacatcgg cagccatgga 600 agctgataaa tttgtcttct taaaaaacga agggttaatt gacatatcac ttgcaataaa 660 tgcatgttat gatataataa atgacaaagt acctgtttct ccttatatat gcgcaggtat 720 tggtactgat ttgatttcta tgtttgaagc tacaagtcct aaaatttcct accaaggaaa 780 actgggcatt agttactcta ttaatccgga aacctctgtt ttcatcggtg ggcatttcca 840 caggatcata ggtaatgagt ttagagatat tcctgcaata gtacctagta actcaactac 900 aataagtgga ccacaatttg caacagtaac actaaatgtg tgtcactttg gtttagaact 960 tggaggaaga tttaacttct aattttattg ttgccacata ttaaaaatga tctaaacttg 1020 tttttawtat tgctacatac aaaaaaagaa aaatagtggc aaaagaatgt agcaataaga 1080 gggggggggg ggaccaaatt tatcttctat gcttcccaag ttttttcycg ctatttatga 1140 cttaaacaac agaaggtaat atcctcacgg aaaacttatc ttcaaatatt ttatttatta 1200 ccaatcttat ataatatatt aaatttctct tacaaaaatc actagtattt tataccaaaa 1260 tatatattct gacttgcttt tcttctgcac ttctactatt tttaatttat ttgtcactat 1320 taggttataa taawatgaat tgcmaaagat ttttcatagc aagtgcattg atatcactaa 1380 tgtctttctt acctagcgta tctttttctg aatcaataca tgaagataat ataaatggta 1440 acttttacat tagtgcaaag tatatgccaa gtgcctcaca ctttggcgta ttttcagtta 1500 aagaagagaa aaacacaaca actggagttt tcggattaaa acaagattgg gacggagcaa 1560 cactaaagga tgcaagcwgc agccacacaw tagacccaag tacaatg 1607 2 278 PRT Ehrlichia canis amino acid sequence of E. canis p28-7 protein 2 Met Asn Cys Lys Lys Ile Leu Ile Thr Thr Ala Leu Ile Ser Leu 5 10 15 Met Tyr Ser Ile Pro Ser Ile Ser Phe Ser Asp Thr Ile Gln Asp 20 25 30 Gly Asn Met Gly Gly Asn Phe Tyr Ile Ser Gly Lys Tyr Val Pro 35 40 45 Ser Val Ser His Phe Gly Ser Phe Ser Ala Lys Glu Glu Ser Lys 50 55 60 Ser Thr Val Gly Val Phe Gly Leu Lys His Asp trp Asp Gly Ser 65 70 75 Pro Ile Leu Lys Asn Lys His Ala Asp Phe Thr Val Pro Asn Tyr 80 85 90 Ser Phe Arg Tyr Glu Asn Asn Pro Phe Leu Gly Phe Ala Gly Ala 95 100 105 Ile Gly Tyr Ser Met Gly Gly Pro Arg Ile Glu Phe Glu Ile Ser 110 115 120 Tyr Glu Ala Phe Asp Val Lys Ser Pro Asn Ile Asn Tyr Gln Asn 125 130 135 Asp Ala His Arg Tyr Cys Ala Leu Ser His His Thr Ser Ala Ala 140 145 150 Met Glu Ala Asp Lys Phe Val Phe Leu Lys Asn Glu Gly Leu Ile 155 160 165 Asp Ile Ser Leu Ala Ile Asn Ala Cys Tyr Asp Ile Ile Asn Asp 170 175 180 Lys Val Pro Val Ser Pro Tyr Ile Cys Ala Gly Ile Gly Thr Asp 185 190 195 Leu Ile Ser Met Phe Glu Ala Thr Ser Pro Lys Ile Ser Tyr Gln 200 205 210 Gly Lys Leu Gly Ile Ser Tyr Ser Ile Asn Pro Glu Thr Ser Val 215 220 225 Phe Ile Gly Gly His Phe His Arg Ile Ile Gly Asn Glu Phe Arg 230 235 240 Asp Ile Pro Ala Ile Val Pro Ser Asn Ser Thr Thr Ile Ser Gly 245 250 255 Pro Gln Phe Ala Thr Val Thr Leu Asn Val Cys His Phe Gly Leu 260 265 270 Glu Leu Gly Gly Arg Phe Asn Phe 275 3 849 DNA Ehrlichia canis mat_peptide nucleic acid sequence of p28-5 3 atgaattgta aaaaagtttt cacaataagt gcattgatat catccatata cttcctacct 60 aatgtctcat actctaaccc agtatatggt aacagtatgt atggtaattt ttacatatca 120 ggaaagtaca tgccaagtgt tcctcatttt ggaatttttt cagctgaaga agagaaaaaa 180 aagacaactg tagtatatgg cttaaaagaa aactgggcag gagatgcaat atctagtcaa 240 agtccagatg ataattttac cattcgaaat tactcattca agtatgcaag caacaagttt 300 ttagggtttg cagtagctat tggttactcg ataggcagtc caagaataga agttgagatg 360 tcttatgaag catttgatgt gaaaaatcca ggtgataatt acaaaaacgg tgcttacagg 420 tattgtgctt tatctcatca agatgatgcg gatgatgaca tgactagtgc aactgacaaa 480 tttgtatatt taattaatga aggattactt aacatatcat ttatgacaaa catatgttat 540 gaaacagcaa gcaaaaatat acctctctct ccttacatat gtgcaggtat tggtactgat 600 ttaattcaca tgtttgaaac tacacatcct aaaatttctt atcaaggaaa gctagggttg 660 gcctacttcg taagtgcaga gtcttcggtt tcttttggta tatattttca taaaattata 720 aataataagt ttaaaaatgt tccagccatg gtacctatta actcagacga gatagtagga 780 ccacagtttg caacagtaac attaaatgta tgctactttg gattagaact tggatgtagg 840 ttcaacttc 849 4 283 PRT Ehrlichia canis amino acid sequence of p28-5 protein 4 Met Asn Cys Lys Lys Val Phe Thr Ile Ser Ala Leu Ile Ser Ser 5 10 15 Ile Tyr Phe Leu Pro Asn Val Ser Tyr Ser Asn Pro Val Tyr Gly 20 25 30 Asn Ser Met Tyr Gly Asn Phe Tyr Ile Ser Gly Lys Tyr Met Pro 35 40 45 Ser Val Pro His Phe Gly Ile Phe Ser Ala Glu Glu Glu Lys Lys 50 55 60 Lys Thr Thr Val Val Tyr Gly Leu Lys Glu Asn Trp Ala Gly Asp 65 70 75 Ala Ile Ser Ser Gln Ser Pro Asp Asp Asn Phe Thr Ile Arg Asn 80 85 90 Tyr Ser Phe Lys Tyr Ala Ser Asn Lys Phe Leu Gly Phe Ala Val 95 100 105 Ala Ile Gly Tyr Ser Ile Gly Ser Pro Arg Ile Glu Val Glu Met 110 115 120 Ser Tyr Glu Ala Phe Asp Val Lys Asn Pro Gly Asp Asn Tyr Lys 125 130 135 Asn Gly Ala Tyr Arg Tyr Cys Ala Leu Ser His Gln Asp Asp Ala 140 145 150 Asp Asp Asp Met Thr Ser Ala Thr Asp Lys Phe Val Tyr Leu Ile 155 160 165 Asn Glu Gly Leu Leu Asn Ile Ser Phe Met Thr Asn Ile Cys Tyr 170 175 180 Glu Thr Ala Ser Lys Asn Ile Pro Leu Ser Pro Tyr Ile Cys Ala 185 190 195 Gly Ile Gly Thr Asp Leu Ile His Met Phe Glu Thr Thr His Pro 200 205 210 Lys Ile Ser Tyr Gln Gly Lys Leu Gly Leu Ala Tyr Phe Val Ser 215 220 225 Ala Glu Ser Ser Val Ser Phe Gly Ile Tyr Phe His Lys Ile Ile 230 235 240 Asn Asn Lys Phe Lys Asn Val Pro Ala Met Val Pro Ile Asn Ser 245 250 255 Asp Glu Ile Val Gly Pro Gln Phe Ala Thr Val Thr Leu Asn Val 260 265 270 Cys Tyr Phe Gly Leu Glu Leu Gly Cys Arg Phe Asn Phe 275 280 5 840 DNA Ehrlichia canis mat_peptide nucleic acid sequence of p28-6 5 atgaattgca aaaaaattct tataacaact gcattaatgt cattaatgta ctatgctcca 60 agcatatctt tttctgatac tatacaagac gataacactg gtagcttcta catcagtgga 120 aaatatgtac caagtgtttc acattttggt gttttctcag ctaaagaaga aagaaactca 180 actgttggag tttttggatt aaaacatgat tggaatggag gtacaatatc taactcttct 240 ccagaaaata tattcacagt tcaaaattat tcgtttaaat acgaaaacaa cccattctta 300 gggtttgcag gagctattgg ttattcaatg ggtggcccaa gaatagaact tgaagttctg 360 tacgagacat tcgatgtgaa aaatcagaac aataattata agaacggcgc acacagatac 420 tgtgctttat ctcatcatag ttcagcaaca agcatgtcct ccgcaagtaa caaatttgtt 480 ttcttaaaaa atgaagggtt aattgactta tcatttatga taaatgcatg ctatgacata 540 ataattgaag gaatgccttt ttcaccttat atttgtgcag gtgttggtac tgatgttgtt 600 tccatgtttg aagctataaa tcctaaaatt tcttaccaag gaaaactagg attaggttat 660 agtataagtt cagaagcctc tgtttttatc ggtggacact ttcacagagt cataggtaat 720 gaatttagag acatccctgc tatggttcct agtggatcaa atcttccaga aaaccaattt 780 gcaatagtaa cactaaatgt gtgtcacttt ggcatagaac ttggaggaag atttaacttc 840 6 280 PRT Ehrlichia canis amino acid sequence of p28-6 protein 6 Met Asn Cys Lys Lys Ile Leu Ile Thr Thr Ala Leu Met Ser Leu 5 10 15 Met Tyr Tyr Ala Pro Ser Ile Ser Phe Ser Asp Thr Ile Gln Asp 20 25 30 Asp Asn Thr Gly Ser Phe Tyr Ile Ser Gly Lys Tyr Val Pro Ser 35 40 45 Val Ser His Phe Gly Val Phe Ser Ala Lys Glu Glu Arg Asn Ser 50 55 60 Thr Val Gly Val Phe Gly Leu Lys His Asp Trp Asn Gly Gly Thr 65 70 75 Ile Ser Asn Ser Ser Pro Glu Asn Ile Phe Thr Val Gln Asn Tyr 80 85 90 Ser Phe Lys Tyr Glu Asn Asn Pro Phe Leu Gly Phe Ala Gly Ala 95 100 105 Ile Gly Tyr Ser Met Gly Gly Pro Arg Ile Glu Leu Glu Val Leu 110 115 120 Tyr Glu Thr Phe Asp Val Lys Asn Gln Asn Asn Asn Tyr Lys Asn 125 130 135 Gly Ala His Arg Tyr Cys Ala Leu Ser His His Ser Ser Ala Thr 140 145 150 Ser Met Ser Ser Ala Ser Asn Lys Phe Val Phe Leu Lys Asn Glu 155 160 165 Gly Leu Ile Asp Leu Ser Phe Met Ile Asn Ala Cys Tyr Asp Ile 170 175 180 Ile Ile Glu Gly Met Pro Phe Ser Pro Tyr Ile Cys Ala Gly Val 185 190 195 Gly Thr Asp Val Val Ser Met Phe Glu Ala Ile Asn Pro Lys Ile 200 205 210 Ser Tyr Gln Gly Lys Leu Gly Leu Gly Tyr Ser Ile Ser Ser Glu 215 220 225 Ala Ser Val Phe Ile Gly Gly His Phe His Arg Val Ile Gly Asn 230 235 240 Glu Phe Arg Asp Ile Pro Ala Met Val Pro Ser Gly Ser Asn Leu 245 250 255 Pro Glu Asn Gln Phe Ala Ile Val Thr Leu Asn Val Cys His Phe 260 265 270 Gly Ile Glu Leu Gly Gly Arg Phe Asn Phe 275 280 7 133 PRT Ehrlichia canis partial amino acid sequence of p28-5 protein 7 Met Asn Cys Lys Lys Val Phe Thr Ile Ser Ala Leu Ile Ser Ser 5 10 15 Ile Tyr Phe Leu Pro Asn Val Ser Tyr Ser Asn Pro Val Tyr Gly 20 25 30 Asn Ser Met Tyr Gly Asn Phe Tyr Ile Ser Gly Lys Tyr Met Pro 35 40 45 Ser Val Pro His Phe Gly Ile Phe Ser Ala Glu Glu Glu Lys Lys 50 55 60 Lys Thr Thr Val Val Tyr Gly Leu Lys Glu Asn Trp Ala Gly Asp 65 70 75 Ala Ile Ser Ser Gln Ser Pro Asp Asp Asn Phe Thr Ile Arg Asn 80 85 90 Tyr Ser Phe Lys Tyr Ala Ser Asn Lys Phe Leu Gly Phe Ala Val 95 100 105 Ala Ile Gly Tyr Ser Ile Gly Ser Pro Arg Ile Glu Val Glu Met 110 115 120 Ser Tyr Glu Ala Phe Asp Val Lys Asn Gln Gly Asn Asn 125 130 8 287 PRT Ehrlichia canis amino acid sequence of p28-4 protien 8 Met Lys Tyr Lys Lys Thr Phe Thr Val Thr Ala Leu Val Leu Leu 5 10 15 Thr Ser Phe Thr His Phe Ile Pro Phe Tyr Ser Pro Ala Arg Ala 20 25 30 Ser Thr Ile His Asn Phe Tyr Ile Ser Gly Lys Tyr Met Pro Thr 35 40 45 Ala Ser His Phe Gly Ile Phe Ser Ala Lys Glu Glu Gln Ser Phe 50 55 60 Thr Lys Val Leu Val Gly Leu Asp Gln Arg Leu Ser His Asn Ile 65 70 75 Ile Asn Asn Asn Asp Thr Ala Lys Ser Leu Lys Val Gln Asn Tyr 80 85 90 Ser Phe Lys Tyr Lys Asn Asn Pro Phe Leu Gly Phe Ala Gly Ala 95 100 105 Ile Gly Tyr Ser Ile Gly Asn Ser Arg Ile Glu Leu Glu Val Ser 110 115 120 His Glu Ile Phe Asp Thr Lys Asn Pro Gly Asn Asn Tyr Leu Asn 125 130 135 Asp Ser His Lys Tyr Cys Ala Leu Ser His Gly Ser His Ile Cys 140 145 150 Ser Asp Gly Asn Ser Gly Asp Trp Tyr Thr Ala Lys Thr Asp Lys 155 160 165 Phe Val Leu Leu Lys Asn Glu Gly Leu Leu Asp Val Ser Phe Met 170 175 180 Leu Asn Ala Cys Tyr Asp Ile Thr Thr Glu Lys Met Pro Phe Ser 185 190 195 Pro Tyr Ile Cys Ala Gly Ile Gly Thr Asp Leu Ile Ser Met Phe 200 205 210 Glu Thr Thr Gln Asn Lys Ile Ser Tyr Gln Gly Lys Leu Gly Leu 215 220 225 Asn Tyr Thr Ile Asn Ser Arg Val Ser Val Phe Ala Gly Gly His 230 235 240 Phe His Lys Val Ile Gly Asn Glu Phe Lys Gly Ile Pro Thr Leu 245 250 255 Leu Pro Asp Gly Ser Asn Ile Lys Val Gln Gln Ser Ala Thr Val 260 265 270 Thr Leu Asp Val Cys His Phe Gly Leu Glu Ile Gly Ser Arg Phe 275 280 285 Phe Phe 9 281 PRT Ehrlichia chaffeensis amino acid sequence of E. chaffeensis P28 9 Met Asn Tyr Lys Lys Val Phe Ile Thr Ser Ala Leu Ile Ser Leu 5 10 15 Ile Ser Ser Leu Pro Gly Val Ser Phe Ser Asp Pro Ala Gly Ser 20 25 30 Gly Ile Asn Gly Asn Phe Tyr Ile Ser Gly Lys Tyr Met Pro Ser 35 40 45 Ala Ser His Phe Gly Val Phe Ser Ala Lys Glu Glu Arg Asn Thr 50 55 60 Thr Val Gly Val Phe Gly Leu Lys Gln Asn Trp Asp Gly Ser Ala 65 70 75 Ile Ser Asn Ser Ser Pro Asn Asp Val Phe Thr Val Ser Asn Tyr 80 85 90 Ser Phe Lys Tyr Glu Asn Asn Pro Phe Leu Gly Phe Ala Gly Ala 95 100 105 Ile Gly Tyr Ser Met Asp Gly Pro Arg Ile Glu Leu Glu Val Ser 110 115 120 Tyr Glu Thr Phe Asp Val Lys Asn Gln Gly Asn Asn Tyr Lys Asn 125 130 135 Glu Ala His Arg Tyr Cys Ala Leu Ser His Asn Ser Ala Ala Asp 140 145 150 Met Ser Ser Ala Ser Asn Asn Phe Val Phe Leu Lys Asn Glu Gly 155 160 165 Leu Leu Asp Ile Ser Phe Met Leu Asn Ala Cys Tyr Asp Val Val 170 175 180 Gly Glu Gly Ile Pro Phe Ser Pro Tyr Ile Cys Ala Gly Ile Gly 185 190 195 Thr Asp Leu Val Ser Met Phe Glu Ala Thr Asn Pro Lys Ile Ser 200 205 210 Tyr Gln Gly Lys Leu Gly Leu Ser Tyr Ser Ile Ser Pro Glu Ala 215 220 225 Ser Val Phe Ile Gly Gly His Phe His Lys Val Ile Gly Asn Glu 230 235 240 Phe Arg Asp Ile Pro Thr Ile Ile Pro Thr Gly Ser Thr Leu Ala 245 250 255 Gly Lys Gly Asn Tyr Pro Ala Ile Val Ile Leu Asp Val Cys His 260 265 270 Phe Gly Ile Glu Leu Gly Gly Arg Phe Ala Phe 275 280 10 283 PRT Ehrlichia chaffeensis amino acid sequence of E. chaffeensis OMP-1B 10 Met Asn Tyr Lys Lys Ile Phe Val Ser Ser Ala Leu Ile Ser Leu 5 10 15 Met Ser Ile Leu Pro Tyr Gln Ser Phe Ala Asp Pro Val Thr Ser 20 25 30 Asn Asp Thr Gly Ile Asn Asp Ser Arg Glu Gly Phe Tyr Ile Ser 35 40 45 Val Lys Tyr Asn Pro Ser Ile Ser His Phe Arg Lys Phe Ser Ala 50 55 60 Glu Glu Ala Pro Ile Asn Gly Asn Thr Ser Ile Thr Lys Lys Val 65 70 75 Phe Gly Leu Lys Lys Asp Gly Asp Ile Ala Gln Ser Ala Asn Phe 80 85 90 Asn Arg Thr Asp Pro Ala Leu Glu Phe Gln Asn Asn Leu Ile Ser 95 100 105 Gly Phe Ser Gly Ser Ile Gly Tyr Ala Met Asp Gly Pro Arg Ile 110 115 120 Glu Leu Glu Ala Ala Tyr Gln Lys Phe Asp Ala Lys Asn Pro Asp 125 130 135 Asn Asn Asp Thr Asn Ser Gly Asp Tyr Tyr Lys Tyr Phe Gly Leu 140 145 150 Ser Arg Glu Asp Ala Ile Ala Asp Lys Lys Tyr Val Val Leu Lys 155 160 165 Asn Glu Gly Ile Thr Phe Met Ser Leu Met Val Asn Thr Cys Tyr 170 175 180 Asp Ile Thr Ala Glu Gly Val Pro Phe Ile Pro Tyr Ala Cys Ala 185 190 195 Gly Val Gly Ala Asp Leu Ile Asn Val Phe Lys Asp Phe Asn Leu 200 205 210 Lys Phe Ser Tyr Gln Gly Lys Ile Gly Ile Ser Tyr Pro Ile Thr 215 220 225 Pro Glu Val Ser Ala Phe Ile Gly Gly Tyr Tyr His Gly Val Ile 230 235 240 Gly Asn Asn Phe Asn Lys Ile Pro Val Ile Thr Pro Val Val Leu 245 250 255 Glu Gly Ala Pro Gln Thr Thr Ser Ala Leu Val Thr Ile Asp Thr 260 265 270 Gly Tyr Phe Gly Gly Glu Val Gly Val Arg Phe Thr Phe 275 280 11 280 PRT Ehrlichia chaffeensis amino acid sequence of E. chaffeensis OMP-1C 11 Met Asn Cys Lys Lys Phe Phe Ile Thr Thr Ala Leu Ala Leu Pro 5 10 15 Met Ser Phe Leu Pro Gly Ile Leu Leu Ser Glu Pro Val Gln Asp 20 25 30 Asp Ser Val Ser Gly Asn Phe Tyr Ile Ser Gly Lys Tyr Met Pro 35 40 45 Ser Ala Ser His Phe Gly Val Phe Ser Ala Lys Glu Glu Lys Asn 50 55 60 Pro Thr Val Ala Leu Tyr Gly Leu Lys Gln Asp Trp Asn Gly Val 65 70 75 Ser Ala Ser Ser His Ala Asp Ala Asp Phe Asn Asn Lys Gly Tyr 80 85 90 Ser Phe Lys Tyr Glu Asn Asn Pro Phe Leu Gly Phe Ala Gly Ala 95 100 105 Ile Gly Tyr Ser Met Gly Gly Pro Arg Ile Glu Phe Glu Val Ser 110 115 120 Tyr Glu Thr Phe Asp Val Lys Asn Gln Gly Gly Asn Tyr Lys Asn 125 130 135 Asp Ala His Arg Tyr Cys Ala Leu Asp Arg Lys Ala Ser Ser Thr 140 145 150 Asn Ala Thr Ala Ser His Tyr Val Leu Leu Lys Asn Glu Gly Leu 155 160 165 Leu Asp Ile Ser Leu Met Leu Asn Ala Cys Tyr Asp Val Val Ser 170 175 180 Glu Gly Ile Pro Phe Ser Pro Tyr Ile Cys Ala Gly Val Gly Thr 185 190 195 Asp Leu Ile Ser Met Phe Glu Ala Ile Asn Pro Lys Ile Ser Tyr 200 205 210 Gln Gly Lys Leu Gly Leu Ser Tyr Ser Ile Asn Pro Glu Ala Ser 215 220 225 Val Phe Val Gly Gly His Phe His Lys Val Ala Gly Asn Glu Phe 230 235 240 Arg Asp Ile Ser Thr Leu Lys Ala Phe Ala Thr Pro Ser Ser Ala 245 250 255 Ala Thr Pro Asp Leu Ala Thr Val Thr Leu Ser Val Cys His Phe 260 265 270 Gly Val Glu Leu Gly Gly Arg Phe Asn Phe 275 280 12 286 PRT Ehrlichia chaffeensis amino acid sequence of E. chaffeensis OMP-1D 12 Met Asn Cys Glu Lys Phe Phe Ile Thr Thr Ala Leu Thr Leu Leu 5 10 15 Met Ser Phe Leu Pro Gly Ile Ser Leu Ser Asp Pro Val Gln Asp 20 25 30 Asp Asn Ile Ser Gly Asn Phe Tyr Ile Ser Gly Lys Tyr Met Pro 35 40 45 Ser Ala Ser His Phe Gly Val Phe Ser Ala Lys Glu Glu Arg Asn 50 55 60 Thr Thr Val Gly Val Phe Gly Ile Glu Gln Asp Trp Asp Arg Cys 65 70 75 Val Ile Ser Arg Thr Thr Leu Ser Asp Ile Phe Thr Val Pro Asn 80 85 90 Tyr Ser Phe Lys Tyr Glu Asn Asn Leu Phe Ser Gly Phe Ala Gly 95 100 105 Ala Ile Gly Tyr Ser Met Asp Gly Pro Arg Ile Glu Leu Glu Val 110 115 120 Ser Tyr Glu Ala Phe Asp Val Lys Asn Gln Gly Asn Asn Tyr Lys 125 130 135 Asn Glu Ala His Arg Tyr Tyr Ala Leu Ser His Leu Leu Gly Thr 140 145 150 Glu Thr Gln Ile Asp Gly Ala Gly Ser Ala Ser Val Phe Leu Ile 155 160 165 Asn Glu Gly Leu Leu Asp Lys Ser Phe Met Leu Asn Ala Cys Tyr 170 175 180 Asp Val Ile Ser Glu Gly Ile Pro Phe Ser Pro Tyr Ile Cys Ala 185 190 195 Gly Ile Gly Ile Asp Leu Val Ser Met Phe Glu Ala Ile Asn Pro 200 205 210 Lys Ile Ser Tyr Gln Gly Lys Leu Gly Leu Ser Tyr Pro Ile Ser 215 220 225 Pro Glu Ala Ser Val Phe Ile Gly Gly His Phe His Lys Val Ile 230 235 240 Gly Asn Glu Phe Arg Asp Ile Pro Thr Met Ile Pro Ser Glu Ser 245 250 255 Ala Leu Ala Gly Lys Gly Asn Tyr Pro Ala Ile Val Thr Leu Asp 260 265 270 Val Phe Tyr Phe Gly Ile Glu Leu Gly Gly Arg Phe Asn Phe Gln 275 280 285 Leu 13 278 PRT Ehrlichia chaffeensis amino acid sequence of E. chaffeensis OMP-1E 13 Met Asn Cys Lys Lys Phe Phe Ile Thr Thr Ala Leu Val Ser Leu 5 10 15 Met Ser Phe Leu Pro Gly Ile Ser Phe Ser Asp Pro Val Gln Gly 20 25 30 Asp Asn Ile Ser Gly Asn Phe Tyr Val Ser Gly Lys Tyr Met Pro 35 40 45 Ser Ala Ser His Phe Gly Met Phe Ser Ala Lys Glu Glu Lys Asn 50 55 60 Pro Thr Val Ala Leu Tyr Gly Leu Lys Gln Asp Trp Glu Gly Ile 65 70 75 Ser Ser Ser Ser His Asn Asp Asn His Phe Asn Asn Lys Gly Tyr 80 85 90 Ser Phe Lys Tyr Glu Asn Asn Pro Phe Leu Gly Phe Ala Gly Ala 95 100 105 Ile Gly Tyr Ser Met Gly Gly Pro Arg Val Glu Phe Glu Val Ser 110 115 120 Tyr Glu Thr Phe Asp Val Lys Asn Gln Gly Asn Asn Tyr Lys Asn 125 130 135 Asp Ala His Arg Tyr Cys Ala Leu Gly Gln Gln Asp Asn Ser Gly 140 145 150 Ile Pro Lys Thr Ser Lys Tyr Val Leu Leu Lys Ser Glu Gly Leu 155 160 165 Leu Asp Ile Ser Phe Met Leu Asn Ala Cys Tyr Asp Ile Ile Asn 170 175 180 Glu Ser Ile Pro Leu Ser Pro Tyr Ile Cys Ala Gly Val Gly Thr 185 190 195 Asp Leu Ile Ser Met Phe Glu Ala Thr Asn Pro Lys Ile Ser Tyr 200 205 210 Gln Gly Lys Leu Gly Leu Ser Tyr Ser Ile Asn Pro Glu Ala Ser 215 220 225 Val Phe Ile Gly Gly His Phe His Lys Val Ile Gly Asn Glu Phe 230 235 240 Arg Asp Ile Pro Thr Leu Lys Ala Phe Val Thr Ser Ser Ala Thr 245 250 255 Pro Asp Leu Ala Ile Val Thr Leu Ser Val Cys His Phe Gly Ile 260 265 270 Glu Leu Gly Gly Arg Phe Asn Phe 275 14 280 PRT Ehrlichia chaffeensis amino acid sequence of E. chaffeensis OMP-1F 14 Met Asn Cys Lys Lys Phe Phe Ile Thr Thr Thr Leu Val Ser Leu 5 10 15 Met Ser Phe Leu Pro Gly Ile Ser Phe Ser Asp Ala Val Gln Asn 20 25 30 Asp Asn Val Gly Gly Asn Phe Tyr Ile Ser Gly Lys Tyr Val Pro 35 40 45 Ser Val Ser His Phe Gly Val Phe Ser Ala Lys Gln Glu Arg Asn 50 55 60 Thr Thr Thr Gly Val Phe Gly Leu Lys Gln Asp Trp Asp Gly Ser 65 70 75 Thr Ile Ser Lys Asn Ser Pro Glu Asn Thr Phe Asn Val Pro Asn 80 85 90 Tyr Ser Phe Lys Tyr Glu Asn Asn Pro Phe Leu Gly Phe Ala Gly 95 100 105 Ala Val Gly Tyr Leu Met Asn Gly Pro Arg Ile Glu Leu Glu Met 110 115 120 Ser Tyr Glu Thr Phe Asp Val Lys Asn Gln Gly Asn Asn Tyr Lys 125 130 135 Asn Asp Ala His Lys Tyr Tyr Ala Leu Thr His Asn Ser Gly Gly 140 145 150 Lys Leu Ser Asn Ala Gly Asp Lys Phe Val Phe Leu Lys Asn Glu 155 160 165 Gly Leu Leu Asp Ile Ser Leu Met Leu Asn Ala Cys Tyr Asp Val 170 175 180 Ile Ser Glu Gly Ile Pro Phe Ser Pro Tyr Ile Cys Ala Gly Val 185 190 195 Gly Thr Asp Leu Ile Ser Met Phe Glu Ala Ile Asn Pro Lys Ile 200 205 210 Ser Tyr Gln Gly Lys Leu Gly Leu Ser Tyr Ser Ile Ser Pro Glu 215 220 225 Ala Ser Val Phe Val Gly Gly His Phe His Lys Val Ile Gly Asn 230 235 240 Glu Phe Arg Asp Ile Pro Ala Met Ile Pro Ser Thr Ser Thr Leu 245 250 255 Thr Gly Asn His Phe Thr Ile Val Thr Leu Ser Val Cys His Phe 260 265 270 Gly Val Glu Leu Gly Gly Arg Phe Asn Phe 275 280 15 284 PRT Cowdria ruminantium amino acid sequence of C. ruminantium MAP-1 15 Met Asn Cys Lys Lys Ile Phe Ile Thr Ser Thr Leu Ile Ser Leu 5 10 15 Val Ser Phe Leu Pro Gly Val Ser Phe Ser Asp Val Ile Gln Glu 20 25 30 Glu Asn Asn Pro Val Gly Ser Val Tyr Ile Ser Ala Lys Tyr Met 35 40 45 Pro Thr Ala Ser His Phe Gly Lys Met Ser Ile Lys Glu Asp Ser 50 55 60 Arg Asp Thr Lys Ala Val Phe Gly Leu Lys Lys Asp Trp Asp Gly 65 70 75 Val Lys Thr Pro Ser Gly Asn Thr Asn Ser Ile Phe Thr Glu Lys 80 85 90 Asp Tyr Ser Phe Lys Tyr Glu Asn Asn Pro Phe Leu Gly Phe Ala 95 100 105 Gly Ala Val Gly Tyr Ser Met Asn Gly Pro Arg Ile Glu Phe Glu 110 115 120 Val Ser Tyr Glu Thr Phe Asp Val Arg Asn Pro Gly Gly Asn Tyr 125 130 135 Lys Asn Asp Ala His Met Tyr Cys Ala Leu Asp Thr Ala Ser Ser 140 145 150 Ser Thr Ala Gly Ala Thr Thr Ser Val Met Val Lys Asn Glu Asn 155 160 165 Leu Thr Asp Ile Ser Leu Met Leu Asn Ala Cys Tyr Asp Ile Met 170 175 180 Leu Asp Gly Met Pro Val Ser Pro Tyr Val Cys Ala Gly Ile Gly 185 190 195 Thr Asp Leu Val Ser Val Ile Asn Ala Thr Asn Pro Lys Leu Ser 200 205 210 Tyr Gln Gly Lys Leu Gly Ile Ser Tyr Ser Ile Asn Pro Glu Ala 215 220 225 Ser Ile Phe Ile Gly Gly His Phe His Arg Val Ile Gly Asn Glu 230 235 240 Phe Lys Asp Ile Ala Thr Ser Lys Val Phe Thr Ser Ser Gly Asn 245 250 255 Ala Ser Ser Ala Val Ser Pro Gly Phe Ala Ser Ala Ile Leu Asp 260 265 270 Val Cys His Phe Gly Ile Glu Ile Gly Gly Arg Phe Val Phe 275 280 16 20 DNA artificial sequence primer_bind nucleotides 313-332 of C. ruminantium MAP-1, forward primer 793 for PCR 16 gcaggagctg ttggttactc 20 17 21 DNA artificial sequence primer_bind nucleotides 823-843 of C. ruminantium MAP-1, reverse primer 1330 for PCR 17 ccttcctcca agttctatgc c 21 18 24 DNA artificial sequence primer_bind primer 46f, specific for p28-5 gene 18 atatacttcc tacctaatgt ctca 24 19 20 DNA artificial sequence primer_bind primer used for sequencing 28-kDa protein genes in E. canis 19 agtgcagagt cttcggtttc 20 20 18 DNA artificial sequence primer_bind primer used for sequencing 28-kDa protein genes in E. canis 20 gttacttgcg gaggacat 18 21 24 DNA artificial sequence primer_bind nucleotides 687-710 of E. canis p28-7 primer 394 for PCR 21 gcatttccac aggatcatag gtaa 24 22 24 DNA artificial sequence primer_bind nucleotides 710-687 of E. canis p28-7 primer 394C for PCR 22 ttacctatga tcctgtggaa atgc 24 23 20 DNA artificial sequence primer_bind primer 793C which anneals to a region with E. canis p28-7, used to amplify the intergenic region between gene p28-6 and p28-7 23 gagtaaccaa cagctcctgc 20 24 24 DNA artificial sequence primer_bind primer EC28OM-F complementary to noncoding regions adjacent to the open reading frame of p28-7 24 tctactttgc acttccacta ttgt 24 25 24 DNA artificial sequence primer_bind primer EC28OM-R complementary to noncoding regions adjacent to the open reading frame of p28-7 25 attcttttgc cactattttt cttt 24 26 25 DNA artificial sequence primer_bind primer ECaSA3-2 corresponding to regions within p28-6, used to amplify the intergenic region NC3 between gene p28-6 and p28-7 26 ctaggattag gttatagtat aagtt 25 27 23 PRT Ehrlichia canis PEPTIDE a predicted N-terminal signal peptide of p28-7 and p28-6 27 Met Asn Cys Lys Lys Ile Leu Ile Thr Thr Ala Leu Met Ser Leu 5 10 15 Met Tyr Tyr Ala Pro Ser Ile Ser 20 28 25 PRT Ehrlichia chaffeensis amino acid sequence of N-terminal signal peptide of E. chaffeensis P28 28 Met Asn Tyr Lys Lys Ile Leu Ile Thr Ser Ala Leu Ile Ser Leu 5 10 15 Ile Ser Ser Leu Pro Gly Val Ser Phe Ser 20 25 29 26 PRT Ehrlichia canis amino acid sequence of putative cleavage site of p28-7 29 Met Asn Cys Lys Lys Ile Leu Ile Thr Thr Ala Leu Ile Ser Leu 5 10 15 Met Tyr Ser Ile Pro Ser Ile Ser Ser Phe Ser 20 25 30 299 DNA Ehrlichia canis nucleic acid sequence of intergenic noncoding region 1 (28NC1) 30 taatacttct attgtacatg ttaaaaatag tactagtttg cttctgtggt ttataaacgc 60 aagagagaaa tagttagtaa taaattagaa agttaaatat tagaaaagtc atatgttttt 120 cattgtcatt gatactcaac taaaagtagt ataaatgtta cttattaata attttacgta 180 gtatattaaa tttcccttac aaaagccact agtattttat actaaaagct atactttggc 240 ttgtatttaa tttgtatttt tactactgtt aatttacttt cactgtttct ggtgtaaat 299 31 345 DNA Ehrlichia canis nucleic acid sequence of intergenic noncoding region 2 (28NC2) 31 taatttcgtg gtacacatat cacgaagcta aaattgtttt tttatctctg ctgtatacaa 60 gagaaaaaat agtagtgaaa attacctaac aatatgacag tacaagttta ccaagcttat 120 tctcacaaaa cttcttgtgt cttttatctc tttacaatga aatgtacact tagcttcact 180 actgtagagt gtgtttatca atgctttgtt tattaatact ctacataata tgttaaattt 240 ttcttacaaa actcactagt aatttatact agaatatata ttctgacttg tatttgcttt 300 atacttccac tattgttaat ttattttcac tattttaggt gtaat 345 32 345 DNA Ehrlichia canis nucleic acid sequence of intergenic noncoding region 3 (28NC3) 32 tgattttatt gttgccacat attaaaaatg atctaaactt gtttttatta ttgctacata 60 caaaaaaaag aaaaatagtg gcaaaagaat gtagcaataa gagggggggg ggggactaaa 120 tttaccttct attcttctaa tattctttac tatattcaaa tagcacaact caatgcttcc 180 aggaaaatat gtttctaata ttttatttat taccaatcct tatataatat attaaatttc 240 tcttacaaaa atctctaatg ttttatactt aatatatata ttctggcttg tatttacttt 300 gcacttccac tattgttaat ttattttcac tattttaggt gtaat 345 33 355 DNA Ehrlichia canis nucleic acid sequence of intergenic noncoding region 4 (28NC4) 33 taattttatt gttgccacat attaaaaatg atctaaactt gtttttawta ttgctacata 60 caaaaaaaga aaaatagtgg caaaagaatg tagcaataag aggggggggg gggaccaaat 120 ttatcttcta tgcttcccaa gttttttcyc gctatttatg acttaaacaa cagaaggtaa 180 tatcctcacg gaaaacttat cttcaaatat tttatttatt accaatctta tataatatat 240 taaatttctc ttacaaaaat cactagtatt ttataccaaa atatatattc tgacttgctt 300 ttcttctgca cttctactat ttttaattta tttgtcacta ttaggttata ataaw 355 34 24 DNA artificial sequence primer p28-5-818f 34 ttaaacatat gccacttcgg acta 24 35 28 DNA artificial sequence primer 1191 35 tatgatcgtg taaaattgct gtgagtat 28 36 20 DNA artificial sequence primer ECa28-75C 36 tactggcacg tgctggacta 20 37 22 DNA artificial sequence primer ECa5′-1600 37 caccaataaa tgcagagact tc 22 38 26 DNA artificial sequence primer 3125 38 aatccatcat ttctcattac agtgtg 26 39 879 DNA Ehrlichia canis nucleic acid sequence of E. canis p28-1 39 atgaataata aactcaaatt tactataata aacacagtat tagtatgctt attgtcatta 60 cctaatatat cttcctcaaa ggccataaac aataacgcta aaaagtacta cggattatat 120 atcagtggac aatataaacc cagtgtttct gttttcagta atttttcagt taaagaaacc 180 aatgtcataa ctaaaaacct tatagcttta aaaaaagatg ttgactctat tgaaaccaag 240 actgatgcca gtgtaggtat tagtaaccca tcaaatttta ctatccccta tacagctgta 300 tttcaagata attctgtcaa tttcaatgga actattggtt acacctttgc tgaaggtaca 360 agagttgaaa tagaaggttc ttatgaggaa tttgatgtta aaaaccctgg aggctataca 420 ctaagtgatg cctatcgcta ttttgcatta gcacgtgaaa tgaaaggtaa tagttttaca 480 cctaaagaaa aagtttctaa tagtattttt cacactgtaa tgagaaatga tggattatct 540 ataatatctg ttatagtaaa tgtttgctac gatttctctt tgaacaattt gtcaatatcg 600 ccttacatat gtggaggagc aggggtagat gctatagaat tcttcgatgt attacacatt 660 aagtttgcat atcaaagcaa gctaggtatt gcttattctc taccatctaa cattagtctc 720 tttgctagtt tatattacca taaagtaatg ggcaatcaat ttaaaaattt aaatgtccaa 780 catgttgctg aacttgcaag tatacctaaa attacatccg cagttgctac acttaatatt 840 ggttattttg gaggtgaaat tggtgcaaga ttgacattt 879 40 293 PRT Ehrlichia canis amino acid sequence of E. canis p28-1 protein 40 Met Asn Asn Lys Leu Lys Phe Thr Ile Ile Asn Thr Val Leu Val 5 10 15 Cys Leu Leu Ser Leu Pro Asn Ile Ser Ser Ser Lys Ala Ile Asn 20 25 30 Asn Asn Ala Lys Lys Tyr Tyr Gly Leu Tyr Ile Ser Gly Gln Tyr 35 40 45 Lys Pro Ser Val Ser Val Phe Ser Asn Phe Ser Val Lys Glu Thr 50 55 60 Asn Val Ile Thr Lys Asn Leu Ile Ala Leu Lys Lys Asp Val Asp 65 70 75 Ser Ile Glu Thr Lys Thr Asp Ala Ser Val Gly Ile Ser Asn Pro 80 85 90 Ser Asn Phe Thr Ile Pro Tyr Thr Ala Val Phe Gln Asp Asn Ser 95 100 105 Val Asn Phe Asn Gly Thr Ile Gly Tyr Thr Phe Ala Glu Gly Thr 110 115 120 Arg Val Glu Ile Glu Gly Ser Tyr Glu Glu Phe Asp Val Lys Asn 125 130 135 Pro Gly Gly Tyr Thr Leu Ser Asp Ala Tyr Arg Tyr Phe Ala Leu 140 145 150 Ala Arg Glu Met Lys Gly Asn Ser Phe Thr Pro Lys Glu Lys Val 155 160 165 Ser Asn Ser Ile Phe His Thr Val Met Arg Asn Asp Gly Leu Ser 170 175 180 Ile Ile Ser Val Ile Val Asn Val Cys Tyr Asp Phe Ser Leu Asn 185 190 195 Asn Leu Ser Ile Ser Pro Tyr Ile Cys Gly Gly Ala Gly Val Asp 200 205 210 Ala Ile Glu Phe Phe Asp Val Leu His Ile Lys Phe Ala Tyr Gln 215 220 225 Ser Lys Leu Gly Ile Ala Tyr Ser Leu Pro Ser Asn Ile Ser Leu 230 235 240 Phe Ala Ser Leu Tyr Tyr His Lys Val Met Gly Asn Gln Phe Lys 245 250 255 Asn Leu Asn Val Gln His Val Ala Glu Leu Ala Ser Ile Pro Lys 260 265 270 Ile Thr Ser Ala Val Ala Thr Leu Asn Ile Gly Tyr Phe Gly Gly 275 280 285 Glu Ile Gly Ala Arg Leu Thr Phe 290 293 41 840 DNA Ehrlichia canis nucleic acid sequence of E. canis p28-2 41 atgaattata agaaaattct agtaagaagc gcgttaatct cattaatgtc aatcttacca 60 tatcagtctt ttgcagatcc tgtaggttca agaactaatg ataacaaaga aggcttctac 120 attagtgcaa agtacaatcc aagtatatca cactttagaa aattctctgc tgaagaaact 180 cctattaatg gaacaaattc tctcactaaa aaagttttcg gactaaagaa agatggtgat 240 ataacaaaaa aagacgattt tacaagagta gctccaggca ttgattttca aaataactta 300 atatcaggat tttcaggaag tattggttac tctatggacg gaccaagaat agaacttgaa 360 gctgcatatc aacaatttaa tccaaaaaac accgataaca atgatactga taatggtgaa 420 tactataaac attttgcatt atctcgtaaa gatgcaatgg aagatcagca atatgtagta 480 cttaaaaatg acggcataac ttttatgtca ttgatggtta atacttgcta tgacattaca 540 gctgaaggag tatctttcgt accatatgca tgtgcaggta taggagcaga tcttatcact 600 atttttaaag acctcaatct aaaatttgct taccaaggaa aaataggtat tagttaccct 660 atcacaccag aagtctctgc atttattggt ggatactacc atggcgttat tggtaataaa 720 tttgagaaga tacctgtaat aactcctgta gtattaaatg atgctcctca aaccacatct 780 gcttcagtaa ctcttgacgt tggatacttt ggcggagaaa ttggaatgag gttcaccttc 840 42 280 PRT Ehrlichia canis amino acid sequence of E. canis p28-2 protein 42 Met Asn Tyr Lys Lys Ile Leu Val Arg Ser Ala Leu Ile Ser Leu 5 10 15 Met Ser Ile Leu Pro Tyr Gln Ser Phe Ala Asp Pro Val Gly Ser 20 25 30 Arg Thr Asn Asp Asn Lys Glu Gly Phe Tyr Ile Ser Ala Lys Tyr 35 40 45 Asn Pro Ser Ile Ser His Phe Arg Lys Phe Ser Ala Glu Glu Thr 50 55 60 Pro Ile Asn Gly Thr Asn Ser Leu Thr Lys Lys Val Phe Gly Leu 65 70 75 Lys Lys Asp Gly Asp Ile Thr Lys Lys Asp Asp Phe Thr Arg Val 80 85 90 Ala Pro Gly Ile Asp Phe Gln Asn Asn Leu Ile Ser Gly Phe Ser 95 100 105 Gly Ser Ile Gly Tyr Ser Met Asp Gly Pro Arg Ile Glu Leu Glu 110 115 120 Ala Ala Tyr Gln Gln Phe Asn Pro Lys Asn Thr Asp Asn Asn Asp 125 130 135 Thr Asp Asn Gly Glu Tyr Tyr Lys His Phe Ala Leu Ser Arg Lys 140 145 150 Asp Ala Met Glu Asp Gln Gln Tyr Val Val Leu Lys Asn Asp Gly 155 160 165 Ile Thr Phe Met Ser Leu Met Val Asn Thr Cys Tyr Asp Ile Thr 170 175 180 Ala Glu Gly Val Ser Phe Val Pro Tyr Ala Cys Ala Gly Ile Gly 185 190 195 Ala Asp Leu Ile Thr Ile Phe Lys Asp Leu Asn Leu Lys Phe Ala 200 205 210 Tyr Gln Gly Lys Ile Gly Ile Ser Tyr Pro Ile Thr Pro Glu Val 215 220 225 Ser Ala Phe Ile Gly Gly Tyr Tyr His Gly Val Ile Gly Asn Lys 230 235 240 Phe Glu Lys Ile Pro Val Ile Thr Pro Val Val Leu Asn Asp Ala 245 250 255 Pro Gln Thr Thr Ser Ala Ser Val Thr Leu Asp Val Gly Tyr Phe 260 265 270 Gly Gly Glu Ile Gly Met Arg Phe Thr Phe 275 280 43 828 DNA Ehrlichia canis nucleic acid sequence of E. canis p28-3 43 atgaactgta aaaaaattct tataacaact acattggtat cactaacaat tcttttacct 60 ggcatatctt tctccaaacc aatacatgaa aacaatacta caggaaactt ttacattatt 120 ggaaaatatg taccaagtat ttcacatttt gggaactttt cagctaaaga agaaaaaaac 180 acaacaactg gaatttttgg attaaaagaa tcatggactg gtggtatcat ccttgataaa 240 gaacatgcag cttttaatat cccaaattat tcatttaaat atgaaaataa tccattttta 300 ggatttgcag gggtaattgg ctattcaata ggtagtccaa gaatagaatt tgaagtatca 360 tacgagacat tcgatgtaca aaatccagga gataagttta acaatgatgc acataagtat 420 tgtgctttat ccaatgattc cagtaaaaca atgaaaagtg gtaaattcgt ttttctcaaa 480 aatgaaggat taagtgacat atcactcatg ttaaatgtat gttatgatat aataaacaaa 540 agaatgcctt tttcacctta catatgtgca ggcattggta ctgacttaat attcatgttt 600 gacgctataa accataaagc tgcttatcaa ggaaaattag gttttaatta tccaataagc 660 ccagaagcta acatttctat gggtgtgcac tttcacaaag taacaaacaa cgagtttaga 720 gttcctgttc tattaactgc tggaggactc gctccagata atctatttgc aatagtaaag 780 ttgagtatat gtcattttgg gttagaattt gggtacaggg tcagtttt 828 44 276 PRT Ehrlichia canis amino acid sequence of E. canis p28-3 protein 44 Met Asn Cys Lys Lys Ile Leu Ile Thr Thr Thr Leu Val Ser Leu 5 10 15 Thr Ile Leu Leu Pro Gly Ile Ser Phe Ser Lys Pro Ile His Glu 20 25 30 Asn Asn Thr Thr Gly Asn Phe Tyr Ile Ile Gly Lys Tyr Val Pro 35 40 45 Ser Ile Ser His Phe Gly Asn Phe Ser Ala Lys Glu Glu Lys Asn 50 55 60 Thr Thr Thr Gly Ile Phe Gly Leu Lys Glu Ser Trp Thr Gly Gly 65 70 75 Ile Ile Leu Asp Lys Glu His Ala Ala Phe Asn Ile Pro Asn Tyr 80 85 90 Ser Phe Lys Tyr Glu Asn Asn Pro Phe Leu Gly Phe Ala Gly Val 95 100 105 Ile Gly Tyr Ser Ile Gly Ser Pro Arg Ile Glu Phe Glu Val Ser 110 115 120 Tyr Glu Thr Phe Asp Val Gln Asn Pro Gly Asp Lys Phe Asn Asn 125 130 135 Asp Ala His Lys Tyr Cys Ala Leu Ser Asn Asp Ser Ser Lys Thr 140 145 150 Met Lys Ser Gly Lys Phe Val Phe Leu Lys Asn Glu Gly Leu Ser 155 160 165 Asp Ile Ser Leu Met Leu Asn Val Cys Tyr Asp Ile Ile Asn Lys 170 175 180 Arg Met Pro Phe Ser Pro Tyr Ile Cys Ala Gly Ile Gly Thr Asp 185 190 195 Leu Ile Phe Met Phe Asp Ala Ile Asn His Lys Ala Ala Tyr Gln 200 205 210 Gly Lys Leu Gly Phe Asn Tyr Pro Ile Ser Pro Glu Ala Asn Ile 215 220 225 Ser Met Gly Val His Phe His Lys Val Thr Asn Asn Glu Phe Arg 230 235 240 Val Pro Val Leu Leu Thr Ala Gly Gly Leu Ala Pro Asp Asn Leu 245 250 255 Phe Ala Ile Val Lys Leu Ser Ile Cys His Phe Gly Leu Glu Phe 260 265 270 Gly Tyr Arg Val Ser Phe 275 45 813 DNA Ehrlichia canis nucleic acid sequence of E. canis p28-9 45 atgaattaca aaagatttgt tgtaggtgtt acgctgagta catttgtttt tttcttatct 60 gatggtgctt tttctgatgc aaatttttct gaagggagga gaggacttta tataggtagt 120 cagtataaag ttggtattcc caattttagt aatttttcag ctgaagaaac aattcctggt 180 attacaaaaa agatttttgc gttaggtctt gataagtctg agataaatac tcacagcaat 240 tttacacgat catatgaccc tacttatgca agcagttttg cagggtttag tggtatcatt 300 ggatattatg ttaatgactt tagggtagaa tttgaaggtt cttatgagaa ttttgaacct 360 gaaagacaat ggtaccctga gaatagccaa agctacaaat tttttgcttt gtctcgaaat 420 gctacaaata gtgataataa gtttatagta ctagagaata acggcgttgt tgacaagtct 480 cttaatgtaa atgtttgtta tgatattgct agtggtagta ttcctttagc accttatatg 540 tgtgctggtg ttggtgcaga ttatataaag tttttaggta tatcattgcc taagttttct 600 tatcaagtta agtttggtgt caactaccct ctaaatgtta atactatgtt gtttggtggg 660 ggttattacc ataaggttgt aggtgatagg catgagagag tagaaatagc ttaccatcct 720 actgcattat ctgacgttcc tagaactact tcagcttctg ctactttaaa tactgattat 780 tttggttggg agattggatt tagatttgcg cta 813 46 271 PRT Ehrlichia canis amino acid sequence of E. canis p28-9 protein 46 Met Asn Tyr Lys Arg Phe Val Val Gly Val Thr Leu Ser Thr Phe 5 10 15 Val Phe Phe Leu Ser Asp Gly Ala Phe Ser Asp Ala Asn Phe Ser 20 25 30 Glu Gly Arg Arg Gly Leu Tyr Ile Gly Ser Gln Tyr Lys Val Gly 35 40 45 Ile Pro Asn Phe Ser Asn Phe Ser Ala Glu Glu Thr Ile Pro Gly 50 55 60 Ile Thr Lys Lys Ile Phe Ala Leu Gly Leu Asp Lys Ser Glu Ile 65 70 75 Asn Thr His Ser Asn Phe Thr Arg Ser Tyr Asp Pro Thr Tyr Ala 80 85 90 Ser Ser Phe Ala Gly Phe Ser Gly Ile Ile Gly Tyr Tyr Val Asn 95 100 105 Asp Phe Arg Val Glu Phe Glu Gly Ser Tyr Glu Asn Phe Glu Pro 110 115 120 Glu Arg Gln Trp Tyr Pro Glu Asn Ser Gln Ser Tyr Lys Phe Phe 125 130 135 Ala Leu Ser Arg Asn Ala Thr Asn Ser Asp Asn Lys Phe Ile Val 140 145 150 Leu Glu Asn Asn Gly Val Val Asp Lys Ser Leu Asn Val Asn Val 155 160 165 Cys Tyr Asp Ile Ala Ser Gly Ser Ile Pro Leu Ala Pro Tyr Met 170 175 180 Cys Ala Gly Val Gly Ala Asp Tyr Ile Lys Phe Leu Gly Ile Ser 185 190 195 Leu Pro Lys Phe Ser Tyr Gln Val Lys Phe Gly Val Asn Tyr Pro 200 205 210 Leu Asn Val Asn Thr Met Leu Phe Gly Gly Gly Tyr Tyr His Lys 215 220 225 Val Val Gly Asp Arg His Glu Arg Val Glu Ile Ala Tyr His Pro 230 235 240 Thr Ala Leu Ser Asp Val Pro Arg Thr Thr Ser Ala Ser Ala Thr 245 250 255 Leu Asn Thr Asp Tyr Phe Gly Trp Glu Ile Gly Phe Arg Phe Ala 260 265 270 Leu 271 

What is claimed is:
 1. An isolated DNA sequence encoding a 30-kilodalton protein of Ehrlichia canis, wherein said protein is immunoreactive with anti-Ehrlichia canis serum.
 2. The DNA sequence of claim 1, wherein said protein comprises of an amino acid sequence selected from the group consisting of SEQ ID No. 2, 4, 6, 40, 42, 44 and
 46. 3. The DNA sequence of claim 2, wherein said protein has an N-terminal signal sequence.
 4. The DNA sequence of claim 3, wherein said protein is post-translationally modified to a 28-kilodalton protein.
 5. The DNA sequence of claim 1, wherein said DNA comprises a sequence selected from the group consisting of SEQ ID No. 1, 3, 5, 39, 41, 43 and
 45. 6. The DNA sequence of claim 1, wherein said DNA is contained in a single locus of Ehrlichia canis.
 7. The DNA sequence of claim 6, wherein said locus is a multigene locus of 10,677 base pairs in length.
 8. The DNA sequence of claim 7, wherein said locus contains genes encoding homologous 28-kilodalton proteins of Ehrlichia canis.
 9. The DNA sequence of claim 8, wherein said homologous 28-kilodalton proteins of Ehrlichia canis are selected from the group consisting of p28-1, p28-2, p28-3, p28-4, p28-5, p28-6, p28-7, p28-8 and p28-9.
 10. A vector comprising the DNA sequence of claim
 1. 11. The vector of claim 10, wherein said vector is an expression vector capable of expressing a peptide or polypeptide encoded by a sequence selected from the group consisting of SEQ ID No. 1, 3, 5, 39, 41, 43 and 45 when said expression vector is introduced into a cell.
 12. A recombinant protein comprises of an amino acid sequence selected from the group consisting of SEQ ID No. 2, 4, 6, 40, 42, 44 and
 46. 13. The recombinant protein of claim 12, wherein said amino acid sequence is encoded by a nucleic acid segment comprising a sequence selected from the group consisting of SEQ ID No. 1, 3, 5, 39, 41, 43 and
 45. 14. A host cell comprising a nucleic acid segment selected from the group consisting of SEQ ID No. 1, 3, 5, 39, 41, 43 and
 45. 15. A method of producing the recombinant protein of claim 12, comprising the steps of: obtaining a vector that comprises an expression region comprising a sequence encoding the amino acid sequence selected from the group consisting of SEQ ID No. 2, 4, 6, 40, 42, 44 and 46 operatively linked to a promoter; transfecting said vector into a cell; and culturing said cell under conditions effective for expression of said expression region.
 16. An antibody immunoreactive with a polypeptide comprises of an amino acid sequence selected from the group consisting of SEQ ID No. 2, 4, 6, 40, 42, 44 and
 46. 17. A method of inhibiting Ehrlichia canis infection in a subject comprising the steps of: identifying a subject prior to exposure or suspected of being exposed to or infected with Ehrlichia canis; and administering a composition comprising a 28-kDa antigen of Ehrlichia canis in an amount effective to inhibit Ehrlichia canis infection.
 18. The method of claim 17, wherein said 28-kDa antigen is a recombinant protein comprising an amino acid sequence selected from the group consisting of SEQ ID No. 2, 4, 6, 40, 42, 44 and
 46. 19. The method of claim 18, wherein said recombinant protein is encoded by a gene comprising a sequence selected from the group consisting of SEQ ID No. 1, 3, 5, 39, 41, 43 and
 45. 20. The method of claim 17, wherein said composition comprising a 28-kDa antigen is dispersed in a pharmaceutically acceptable carrier. 